VAC Phi 200 KT88 tube stereo/mono power amp 2x100w stereo / 200w mono

VA10 AP PHI200
NZ$ 16,995.00 ea (incl. GST)
VAC

We Build the World's Finest Audio Components

New
ULTRA AUDIO - given the “Select Audio Component” award
Garrett Hongo of Ultra Audio said: Kevin Hayes has come up with something very special in the Phi 200: a tubed stereo amplifier with the speed, grip, and top-end extension of solid-state, yet with the flow, sparkle, and treble sweetness of tubes. it's a serious high-end investment, but it deserves to be considered by anyone who's interested in the cutting edge of audio engineering. The gist: Stereo amp that seems to produce the best of both the tube and solid-state worlds.

“It is critical in manufacturing perfectionist speakers to use related components that reveal all that’s possible; especially in resolution, tonality, dynamics and sound-staging. To this end we’ve evaluated and tried a vast array of the highest end equipment available. VAC’s amplifiers and preamps have turned out to be references of the highest order, and not coincidentally, terrifically enjoyable to listen to” 
- Alon Wolf, Owner, Magico Loudspeakers 

“I certainly feel better every time I use VAC gear in the systems I build. I do mean every time. If there has been one amplifier which has never failed me when reaching for top shelf sound, it is the Phi 200... VAC equipment has an uncharacteristically big, beautiful sound. ... The conclusion is clear: the balance of power, fullness, and correctness is unparalleled... The VAC sound is audio-writ large but properly proportioned; it is elegant, opulent and ebullient. The vastness and spatiality of the soundstage with the Phi 200 is quite surprising when heard for the first time... Their quality, reliability and unimpeachable sound earn them a resounding recommendation.”
DaGoGo,

The VAC Phi Alpha 200 is the finest combination of value & sound VAC has ever offered, being a more affordable embodiment of the circuits & technologies used in their premier Phi 300.1.

Phi 200 Power Amplifier

Although VAC’s smallest and least expensive power amplifier, the Phi 200 yields fidelity sound far superior to any of our previous award-winning instruments. Through careful voicing and quality control, the “jump” factor of the sound suggest far more than the measured 100+ watts per channel in Stereo mode / 200w in Mono mode. With the flip of a switch, the input circuit is rewired from a single-ended input to fully balanced operation; another switch converts it from stereo operation into a true monoblock for greater power and control.

Versatility

The 90-pound VAC Phi 200 is a 100+-watt-per-channel version of the VAC Phi 300.1a, also user-switchable to 200+ watt mono operation. Both fully balanced and single-ended input modes are supported; by switch setting, the front end circuitry is rearranged to be correct and optimal for the selected mode. The ability of the user to set the amplifier for stereo or mono operation allows both freedom of application (biamp one day, monoblocks the next) and the ability to pace the development of their system. One can start with one Phi 200 in stereo mode today, and add a second one later for additional power and true monoblock performance.

Discreet amber indicator lights tell you when the output tubes are biased for ideal sound. The rugged 2.4 mm non-magnetic chassis is beautifully complimented by the lacquered 9.5 mm fascia. The massive power transformer is fully potted to assure quiet operation. A 12-volt trigger is provided.

Electrical Design

The Phi 200’s wide-band power is developed using the KT88 beam power vacuum tube, exploited to fullest advantage by custom wound 21 section output transformers, each weighing 14 pounds. The Class A direct-coupled low-mu triode input and driver stages are those developed for the Phi 300. The combination results in fast, full, detailed sound.

Both fully balanced and single-ended input modes are supported; by switch setting, the front end circuitry is rearranged to be correct and optimal for the selected mode.

The Phi amplifiers produce the areas of beauty typically associated with good vacuum tube designs, but also go well beyond this, producing bass impact, speed, and dynamics that have converted many adherents of solid state design. 

The Phi 200's wide band power is developed using the KT88 beam power vacuum tube, exploited to fullest advantage by custom wound 21 section output transformers, each weighing 14 pounds. The Class A direct-coupled low-mu triode input and driver stages are those developed for the Phi 300. The combination results in fast, full, detailed sound. You will be surprised by details in your recordings that you had never heard before. The ambience and retrieval of reverb and decay information is particularly startling.

All of the Phi amplifiers produce the areas of beauty typically associated with good vacuum tube designs, but also go well beyond this, producing bass impact, speed, and dynamics that have converted many adherents of solid state design. You will be surprised by details in your recordings that you had never heard before. To many listeners, the single most surprising aspect of the Phi 200's performance is the absolutely full, powerful, dynamic portrayal of the deepest bass notes. You will hear the punch and control normally associated with solid state amplifiers, but coupled with the tunefullness, ambiance, and ring-out that only vacuum tubes seem able to develop. The ability of the user to set the amplifier for stereo or mono operation allows both freedom of application (biamp one day, monoblocks the next) and the ability to pace the development of their system. One can start with one Phi 200 in stereo mode today, and add a second one later for additional power and true monoblock performance. (black or silver)

To many listeners, however, the single most surprising aspect of the Phi 200's performance is the absolutely full, powerful, dynamic portrayal of the deepest bass notes. You will hear the punch and control normally associated with solid state amplifiers, but coupled with the tunefullness, ambiance, and ring-out that only vacuum tubes seem able to develop.

Both fully balanced and single-ended input modes are supported; by switch setting, the front end circuitry is rearranged to be correct and optimal for the selected mode. Discreet amber indicator lights tell you when the output tubes are biased for ideal sound. The rugged 2.4 mm non-magnetic chassis is beautifully complimented by the laquered 9.5 mm fascia. The massive power transformer is fully potted to assure quiet operation. A 12 volt trigger is provided.

The ability of the user to set the amplifier for stereo or mono operation allows both freedom of application (biamp one day, monoblocks the next) and the ability to pace the development of their system. One can start with one Phi 200 in stereo mode today, and add a second one later for additional power and true monoblock performance. 

In the mono mode the Phi 200 really sings. There is not just more power, there is more detail and control.

Bottom line: mono or stereo, the VAC Phi 200 is one of the world's finest amplifiers. 

Specifications

Reviews

Specifications

Wattage
100w+ stereo into 2, 4, and 8 ohms 
200w+ mono mode
Gain - 37 dB, SE / 31 dB, balanced
Frequency Response - 4 Hz to 75 kHz
Power Bandwidth - 13 Hz to 70 kHz
Inputs - Single-ended input via RCA jack, non-inverting / XLR balanced
Outputs - Connections to precisely match loudspeaker loads of 2, 4, and 8 ohms
Tubes - 4x KT88 / 4x 6SN7
Residual Noise - Typically, 700 microvolts at the speaker terminals
Voltage -  factory configured for 100v, 120v, 220v, or 230/240 volts
Power Cord - detachable power cord, standard IEC power receptacle
12-Volt Trigger - included
Illumination - Illuminated logo may be switched off
Finish - Lacquered 9.5 mm. fascia (black or silver)
Warranty - 2yrs parts and labor, excluding tubes (USA, see manual for full details)
Dimensions  - 222H x 452W x 452D mm
Shipping Weight - 90 lbs. (40.9 kg.)
Specifications subject to change and improvement without notice

Reviews

As amps have come and gone, the Phi 200 has remained.......their quality, reliability and unimpeachable sound earn them a resounding recommendation.
Doug Schroeder - Dagogo

Kevin is among the most well read, technically informed tube preamp and amp manufacturers in the entirety of the high-end two-channel world. He is not so concerned with analyzing specifications to death, but rather what works in terms of obtaining the best sound. This review is my most comprehensive to date in terms of an amplifier’s use with other components. I subjected the Phi 200 to more sources, preamps, cables and speakers – systems – than any previously reviewed piece. It yielded top-quality sound with a large body of available components. Kevin’s concern is producing a quality instrument above all. You are paying him for the best amp he can build, and he’s going to make sure you get it. That is why he’s going to listen to it before it ships.

My experience with the Phi 200 is that I can be assured that no matter which loudspeaker I put into the rig I’ll get top quality sound. 

The Phi 200 is a natural winner when it comes to symphonic and chamber music. The flush tonal quality of natural instruments created by the Phi 200 enlivens a score. The Phi 200 is exemplary in capturing the surge of the symphony as it crashes in crescendo, emulating the killer waves of the ferocious hurricane.

The VAC sound is audio-writ large but properly proportioned; it is elegant, opulent and ebullient. The vastness and spatiality of the soundstage with the Phi 200 is quite surprising when heard for the first time. You may have heard many amps with differing power resources, and different levels of clarity. If you have worked primarily with solid-state amps, you likely have not heard the expansiveness a fine tube amp can bring to a system.

Pay Not To Play
I would pay good money to have Kevin Hayes, owner and designer at VAC, listen to an amplifier. If you purchase a Valve Amplification Company product you are paying Kevin to listen to your product extensively before you use it, and you should be elated. He listens to everypiece of gear which leaves VAC’s premises. Again, it is Kevin who listens, not some other worker. He is the final arbiter of sound quality on every piece of VAC gear which is sold. It is a very good thing when a knowledgeable, passionate person is at the helm of an audio company and singularly treats your component as if it is his. That kind of personal service costs more, but brings some distinct advantages to the audiophile searching for top sound.
 
Kevin is among the most well read, technically informed tube preamp and amp manufacturers in the entirety of the high-end two-channel world. When he was a teenager he pored endlessly over a tattered copy of the Radiotron Designer’s Handbook, and remarks that he has, “… collected and read thousands of pieces of literature on the creation, capture and reproduction of sound.” In describing this he states, “I don’t know why God gave me this passion for music and its reproduction, but it’s been part of the fabric of my being for as long as I can remember.” I can relate to that sense, as when I was in grade school I was already glomming onto a 1977 Lloyds all-in-one system (8 track, turntable and receiver), and shortly after assembled my first rig. I also have felt driven to assemble stereo systems in a search for “musical meaning” in sound reproduction. Consequently, this article brings together the deep desires of two men intensely searching for as close to musical perfection as can be achieved in an audio system. Kevin spends an inordinate amount of time listening to a piece of equipment until he deems the design worthy. I have listened to an inordinate amount of gear, looking for the perfect sound. That search for perfect sound has led me to VAC.
 
Transformation of An Audiophile
In younger days, while Kevin was developing into a tube amp impresario, I was not so passionate about tube amps. I came of age during the ascendancy of solid-state technology and was inevitably swept up in it. When I began to assemble stereo systems I was convinced that solid-state trumped tubes on principle. I made the same assumption as thousands of music lovers; the smaller, cheaper, newer technology had to be better. How simplistic that viewpoint was!
 
Lurking in my mind was a misperception that, in some respects, still plagues the populace – that anything arising from an older technology was suspect of being inferior. Perhaps you have witnessed a person who sees a tube preamp or amp declare, “Tubes! I didn’t know they still made audio equipment with tubes.” Unless a person consumes Hi Fi periodicals, visits the right dealer or internet forum, or attends a Hi Fi show, the bias is likely to remain. Tube amps still seem on the face outdated to many and are treated as suspect devices by others. I see comments on audio sites from individuals who approach tubes as though they are inherently untrustworthy, as if they degrade sonically so quickly and have such poor distortion specs that one can’t be certain of their performance. To such individuals, solid-state is nigh unto infallible. I was like that for a long time. Part of it was that I was not into DIY, and could not afford finer tube gear; part of me wanted to believe that I sacrificed nothing sonically for sticking with solid-state because on the whole it was cheaper.
 
Over the years I have slowly been remade as an audiophile, morphing from a staunch solid-state supporter to a tube amplifier enthusiast. With growing experience hearing tube amps in quality systems, I was forced to admit that they have as much, and in some instances more efficacy than solid-state designs. I now find that I am drawn toward tube amplification like the proverbial moth to the flame. I am increasingly using tube preamps and amps in systems by preference.
 
During this process I have also revised my thinking in terms of use of tubes with less efficient speakers. Experience with the amp under review here, the Valve Amplification Company (VAC) Phi 200, has cemented my belief that solid-state is not the only game in town for electrostatic and magnetic planar speakers. In fact, paying attention more to the timbre of the music, a strong argument can be made that tube amps are the ideal for panel speakers; jacking up Watts is certainly not the only variable in attaining a pleasing result with panels.
 
Tubes and TUBES
There are tubes, and then there are some: not all tube amps are created equally. When approaching tube amplification one must determine early on which direction will be taken, the low-power linear circuit topology such as SET (Single-Ended Triode) amps, or larger high-output power stages with push/pull topology and a battery of output tubes. There is an alluring attribute of clarity in many of the simpler, lower power amps which is difficult to match in the higher-powered designs. With economical tube amps, one usually has to make a trade off, purity for power, or vice versa. It is rare to find both in abundance.
 
Having used both types I have at this time concluded that I prefer to trade an extremely small amount of clarity for radically increased power. Ideally, I would never have to do this, but I found myself longing for dynamic power and weight when hearing low-power amps. They simply have a tendency to sound wussy compared to higher-powered tube amps, even when paired with extremely efficient speakers. The search for ultimate-sound low-power amps radically limits the number of speakers to be practically considered, a trade off that I am not willing to make.
 
Given that a system is influenced in terms of signal purity throughout the chain, I determined that I would sacrifice marginally at the amp when it came to clarity and make up the deficiency in the other components, particularly the source. I have found the ability of an amp to create robust dynamic power an aspect too important to skimp on; but the sense of clean power can be enhanced through careful selection of attending components, especially the source and cabling used with the preamp/amp combo.
 
Let it not be misconstrued that I am advocating any intentional lowering of standards in sound quality. When confronted with real-world limitations and budgets for gear, one simply must make choices leading to the best result. In no audio system is there an absolutely perfect route to ideal sound; there are always trade-offs. I seek to trade off the potentially most damaging shortcomings for ones which are potentially least damaging. A good example is the use of power conditioning components, which invariably involve a trade-off of absolute clarity as they extend and complicate the system. One must assess whether the influence of the conditioner is overall a positive or negative.
 
At this point in time I do not typically use power conditioners in systems, as I find that every one I have used has degraded the clarity of the system in an absolute sense. I am the first house in our subdivision and the power transformer sits right outside our back door. I have clean, noise-free power lines and despite trying many power devices which utilize filtering I have always ended up returning to the good ol’ plug-in-the-wall method. This does not mean power treatment is without merit, but simply that I do not benefit greatly from it. Thus, the elimination of the power conditioner improves the overall system clarity and the amplification benefits.
 
A very practical consideration in terms of speaker selection also necessitated this decision to settle on big amps – I enjoy huge panel speakers. These are typically difficult to drive, effectively sidelining smaller tube amps. One possible panacea may be the gain feature of the Ayon Audio CD-5, an extremely fine all-in-one player/preamp, with settings of 4, 6, and 8 Volts output. With it, one has the option of matching smaller amps with less efficient speakers. Save for that indulgence, necessity exists to have ample power to drive a 2-ohm load, and sometimes much lower, typically found in larger panel speakers.
 
Love Affair with Panel Sound
My first experience hearing a panel speaker was in St. Louis at a high-end shop where, shamefully, I cannot recall the name, I was overwhelmed by the majesty of the Magneplanar Tympani. I never dreamed sound could be like that! Over the years I have had the pleasure of hearing a wide variety of pleasing panels. I flipped speakers annually, if not more often, and found myself bouncing between dynamic and planar offerings. In recent years I have been migrating toward full range ESL (Electrostatic Loudspeaker) technology and have adopted the King Sound The King as my reference. Recently, I added a new version of the hybrid dynamic speaker from Legacy Audio, called the Whisper DSW. The Whisper utilizes a 4” magnetic planar midrange, so it also gravitates toward panel sound.
 
As my reference speakers have been upgraded over the past decade, so also has my amplification. In that process, I have expanded from the solid-state end of the amp spectrum to hybrids, to tube amps. This was quite unexpected for someone sold on the merits of solid-state. Once I learned that powerful enough tube amps existed to do the job, I thought that they were all priced into the stratosphere. Wrong. I ended up settling on the compromise position – tube hybrid amplification. My affordable favorite is the capable and beautiful pair of Pathos Classic One MkIII amps operating in mono mode.
 
Of late I have been on a search for a premier amplifier to drive either the DSW or the King. This is no small feat; the Whisper, though having four 15” bass drivers per channel and 95 dB sensitivity is a 4-0hm speaker and an open baffle design. Consequently, it is rated at 22 Hz – 30 kHz +/- 2 dB. It hits 20 Hz comfortably, but to extract larger subwoofer-like bass from it requires an amp with not just enough watts but also higher current. To get both of those in a tube amp usually costs much more than a solid-state amp.
 
On the other end of the speaker spectrum, the Kingsound King is a tough-to-drive electrostatic. It dips to approximately 1.8 Ohms at 20kHz, and though it has a more friendly nominal impedance of 6 Ohms, sensitivity is at 83 dB. These two speakers could hardly be more different from each other! It did not take long to learn that solid-state amps, while providing ample power, introduced problems in terms of sounding technical with one or the other speakers. The Pathi took me way down the road toward perfection with both speakers, but the ultimate answer was not to come until the VAC Phi 200’s showed up at my door.
 
Four lumps of amplification, please!
There are people who take their coffee black and strong. I take my amplification big and strong. Amplification junkies break down into two types; stereo people and biamp/mono people. I’m the latter. Usually, if you give me a speaker with two sets of binding posts the following thought takes possession of my mind immediately, “Four posts… which cable will I bi-wire with and which pair of amps am I going to use?” I have done so many comparisons of amps running stereo compared to passively bi-amped and bi-wired, or actively bi-amped that I no longer wish to assemble my reference system with just one amp. (So sad. Same here. –Ed.)
 
From the time that I first heard the King at CES 2008 and learned that Kevin used it in voicing the Phi 200, he suggested that I might use the amp with the speaker. Later, as I had taken ownership of the speaker, the possibility that I not follow up with a review of the Phi 200 was unthinkable! Seeing that only one unit was driving the speakers at the show, I assumed that one would be sufficient for the review. Kevin offered that two would be superior. But of course! Now that’s impressive; a manufacturer who offers a second amp to get the reviewing job done right! I had seldom encountered that level of commitment to me from a manufacturer in setting up a review system. It speaks volumes to me about how Kevin is only happy when the sound is correct. The suggestion revealed to me that Kevin is keen on obtaining the optimal sound, and had confidence that his amps would perform at an extremely high level in mono mode.
 
At the first California Audio Show, the King was shown with the VAC Phi 200 to much interest and approval. There was a technical issue, as only one Phi 200 drove the pair of speakers but was using the 8-ohm posts versus the anticipated 2-ohm posts. Consequently at higher listening levels the amp was pushed to its limit and did not sound as effortless as it is capable. In my listening at home, I have tested all three settings, 1-2 Ohm, 2-4 Ohm, and 4-8 Ohm, and the King was much more controlled by the Phi 200 with the lower 1-2 Ohm terminals in use. The Phi 200 is the kind of amp that one can play a speaker like the King with confidence in stereo mode and work toward a second unit to operate them in mono mode for ultimate performance.
 
In extended use, the Phi 200 does not run terribly hot; I was surprised at how little heat they generated. The Cambridge Audio Azur 840W, a solid-state design, throws off more heat. Only if left on half a day in a smallish room would I think that they might test the limits of the listener’s temperature-comfort tolerance.
 
Unveiling the Phi 200
Perhaps the term unveiling is too strong; I’m here discussing the unpacking, appearance and operation of the amp. “Dis-crating” a high-quality amp can be a bit like the dance of the seven veils, as each layer is carefully stripped away. Surprisingly, no crate was involved; custom foam pieces cradle the amp in a sturdy double box. The casing and transformer covers are nearly of military thickness, fronted by a slab-like faceplate. As a side note, custom formed foam packing pieces are quite expensive. At the time of the delivery of the Legacy Audio Whisper DSW, I was about to toss out an indistinct smaller foam piece perhaps half a meter long which was lying nearby as the transport materials were being collected. Doug Brown of Legacy Audio requested its return, “You wouldn’t believe how expensive these are!” MSRP on the piece of foam – $30. No wonder manufacturers charge hundreds of dollars for a pair of OEM boxes with foam! Take note, owner, as it can save you serious money to save the packaging.
 
I chortled when I saw daisy chained rubber bands holding a very low tech piece of cloth draped over the thick aluminum face plate. It certainly did the job, as each amp was immaculate. Kevin will not spare a buck to attain ideal sound, but he’s sensible when arranging packaging. He’s not hung up on glam boxes as pretty velour bags inside wooden boxes don’t get the right sound out of a machine. I’ve learned to be less impressed by such things as I work with equipment. Don’t get me wrong, as a thick covering can save a component from shipping damage. I’ve seen more than one speaker’s finish impaired due to flimsy protective transport coverings. Just don’t make the mistake of thinking, “Oooh, high grade bag! This xxxxx has got to sound great!” Some components have great bags and merely acceptable sound. The Phi 200 arrives as a ruby concealed in a paper bag.
 
In terms of finish, black and silver are the two standard VAC colors, but beggars can’t be choosers, so while the Signature Preamp Mk 2 that I reviewed in March 2010 is in graphite color face, the Phi 200s features metallic silver gloss front plate. No matter, VAC gear looks rich and refined with nice, complementary hues. As the Einstein “The Light In The Dark” had a low-profile chassis, so also does the narrow chassis of the Phi 200, in a powder coat matte black finish that is uninterrupted, save for the tubes and backing wall of transformers. Sitting just behind these blocks of impedance transforming windings are the main operational switches.
 
One needs to be careful when handling tube amps as the weight is not necessarily evenly distributed across the chassis’ expanse. Wherever the transformers are, there most of the weight will likely be. In the case of the Phi 200, one must grab the amp nearly at the rear, literally picking it up at ¾ of the way to the back of the unit to prevent it from potentially slipping from one’s grip. It is a good habit to test-lift tube amplifiers to find the balance point. You do not want to be in the middle of transporting one and finding that you chose the wrong place to grab. It’s a scary feeling to have a component turning in your hand because its mass is unevenly distributed. Go about such tasks diligently and save yourself some fear or heartache.
 
Also on the top of the chassis, just in front of each pair of low-level voltage amplifier/phase splitter 6SN7 tubes, are small toggle switches allowing for selection of balanced (XLR) or single-ended (RCA) inputs. Nearby are corresponding holes for the output tubes in the chassis about the diameter of a pencil. These allow access to the bias adjustment points of the amp. A supplied small biasing tool akin to a tiny screwdriver is employed for adjustment of the bias. Behind each KT88-SC kinkless tetrode output tube is a small amber LED for assessing the biasing. This was a painless process as the controls to perform the operation are within easy reach and sight. You may have heard complaints of biasing tube amps being a PITA, but with the Phi 200 it is almost effortless. Using the tool supplied one turns the adjustment until the point at which the LED lights up. Then it is turned back until the LED just turns off. This requires slight movements; no lummoxes need apply.
 
When first installed, one has to baby sit the amp for several bias adjustment steps after the unit is first turned on respectively for 60 seconds, 90 seconds, two minutes, five minutes, and finally after 15-30 minutes. Biasing is also required whenever a tube is changed, and approximately once per month of usage. I found the amp to hold its bias extremely well. I would check often and end up not touching the settings as I could not determine that they had changed. The manual states, “Proper setting is indicated by an LED that is dark when no music is playing, but lights ‘with the beat’ as music is played.” The owner is left to determine how “heavy” the beat is to be. I put on some music with stronger bass line to adjust the bias such that the LED is never off completely but winks almost out before being illuminated by the next beat. When listening to Rapcore or Doom Metal music the light never turned off. Just kidding; I don’t listen to these genres of music.
 
The connections behind the transformers include 15A IEC for power cord, twin sets of binding posts for left and right channels, each having a common/ground post and three posts for 1-2 Ohm, 2-4 Ohm, and 4-8 Ohm to select placement of the positive speaker lead.
 
Phi foibles
There is an aesthetic consideration in the appearance of the Phi 200 which reveals itself when you hook it up; the inputs are behind the transformers, on the top of the chassis. My first reaction is that of appreciated sensibility; it’s far easier to see what you’re doing when setting up the amp than leaning over its side especially if the amps are in an amp stand! Officially, it was done to keep the front-to-back dimension within the space allowed by some cabinets and racks. However, it’s not so captivating to see the mongo power cord arc in the air because it’s too thick to lay flat emerging from the amp’s top mounted IEC receptacle. However, I will gladly endure this slight visual perturbation to use the Phi 200. I weep for any man who can afford this amp and whose wife kills the purchase because the power cord arises into the air. The amp is good enough that I would suggest offering new furniture as compensation. If you have stiff interconnects, they, too, will stick up in the air. If that is a problem, then consider getting longer interconnects and hiding the amps behind the speakers, a tactic which may get you noticeably improved sound.
 
The only other operational quirk I found was the fairly close spacing of 0.75-inch of the Cardas rhodium binding posts, the spacing provision of which is controlled allegedly by the insulation parts supplied by Cardas. Cables with oversized spades are placed too close to be casual about hooking them up. Though it didn’t always appear to be, there was enough room for spades of all cable types used. I made sure to use a binding post wrench, available from Audioquest and Cardas, to prevent possible slippage of the spades.
 
Reading required
Even an Owner’s Manual can reflect on the nature of the designer. The Phi 200’s manual describes features and has no diagrams. It is anticipated that someone who lays out long green for a premium instrument will care enough to read what and what not to do with the amp. Hence, a thorough discussion of the operations in the manual, a walkthrough if you will, describes the experience of using the Phi 200. Starting with the safety notices on the first page, tidbits of advice assist the new owner, among them:
 
Avoid power conditioners that float the ground pin.
A 12V trigger cable can be used to turn the amp on and off via external device.
“Pay close attention to power quality, and be aware that different power cords can alter the sound.” (Bravo! An amp manufacturer who acknowledges the critical nature of power cords!)
Discussion of break in period – approximately 200 hours.
Description of the appearance of tubes operating normally, as well as ones which are “running away”, being destroyed due to excessive current when seated improperly or defective.
Expectations regarding tube life and quality, and VAC selection of its tubes for use with the Phi 200, as well as a list of equivalent tube numbers for tube rolling.
Explanation of Impedance Matching, including the option of using two different impedance output posts for bi-wiring speakers (However, use of 4-8 Ohm posts are required for Mono amp mode with low efficiency speakers like ESLs).
 
As one reads, it becomes clear that Kevin anticipates the new owner to consider his amp an instrument for fine music reproduction. Years of experience as a designer and music enthusiast are coalesced into the Manual, and I recommend careful reference to it.
 
“VAC Facts”
Before delving into discussion of the sound of the Phi 200, I would first like to stimulate your intellect as to the quality of the Phi 200 and VAC gear in general by alluding to what I call “VAC Facts”. These are lesser known packets of knowledge regarding development of the VAC Phi 200 amplifier. These VAC Facts are not merely for entertainment; they are stepping stones to understanding the radical commitment of Kevin Hayes and VAC to bring you the ultimate in audio componentry. Good sound needs to rest on good design principles and good execution. The VAC Facts speak to these and beckon rationally to those who are seeking ultra high-end electronics. As you read them, these testaments to quality will lead you to conclude that VAC authentically cares deeply about product integrity and sound quality.
 
VAC Fact: The Phi 200’s name is not mysterious, as Kevin merely followed convention in audio circles by using a letter of the Greek Alphabet. It may not be an exaggeration to say that half the Greek alphabet has been sourced to name audio components and technologies.
 
VAC Fact: The company builds “Stereo Beam Power” amplifiers. This is a reference to avoidance of standard Tetrode tube designs. According to Kevin, a “beam tetrode” or “kinkless tetrode” causes the electrons to flow in sheets or vertical beams, while repulsing secondary electrons. The design allows for removal of the third grid inside the tube, leaving the anode and cathode. The design is more efficient and yields greater power output than a pentode tube. The KT66 and KT88 are the most successful implementations of this technology in terms of audio quality.
 
VAC Fact: The Phi 200 is a proudly hand built American product. However, it uses a new twist on the power tube, the KT88-SC. Chinese tube maker Shuguang makes it and the 6SN7, both of which are deemed better than NOS tubes! Kevin states that they are notable not only for superb sound, but superior longevity as well.
 
VAC Fact: The Phi 200 was introduced at the 2008 Rocky Mountain Audio Fest (RMAF). Two revisions have been introduced, namely the addition of the MONO switch, and a LOGO ON/OFF switch.
 
VAC Fact: The KT88-SC power tubes operate in ultra-linear mode and feed two 15-pound VAC output transformers based on classic transformer design.
 
VAC Fact: Kevin adheres to a “divide and conquer” philosophy when designing higher-power amps. Per Kevin, “Most designers go for larger parts; I think more along the lines of parallel processing (which, of course, is now all the rage in DACs and computing).” The Phi 200 in Mono mode is very much like his design for a stand-alone mono amp, and benefits from the design of the Phi 300 which was a Stereo/Mono design.
 
VAC Fact: Kevin shares, “If there is one thing I have learned in twenty-plus years in audio design, it is not to prejudge things….. I never assume that a particular tube type, capacitor, circuit topology, etc. must be the best. I do not let my theories tell me about the real world; I try to let the real world correct and refine my theories. To that end, we conduct frequent R&D projects that run contrary to our assumptions. In this way, we learn, grow and produce much better instruments than we could have imagined.” A sign in VAC’s listening room reads: In theory, there is no difference between theory and practice. But, in practice, there is.
 
VAC Fact: The cost is similar to acquire one Phi 300.1a or two Phi 200. Which would yield superior results? According to the designer, “I think the pair of Phi 200 would have a slight edge with regard to detail, extension and dynamics. Ah, but then there are the Mono 300’s…”
 
VAC Fact: The three transformers of the Phi 200 weigh more than half of the amp’s total weight.
 
VAC Fact: The Phi 200, like all VAC products, is designed such that you can leave it to your grandchildren in your will. It is crafted to last. The anticipated first major service is the refreshment of the power supply capacitors – after approximately 40-50 years!
 
VAC Fact: There are eleven sets of speakers currently being used at VAC for the voicing process: five sets of dynamic, three sets of full-range electrostatic, one set of hybrid electrostatic, and two sets of horn speakers! The amp was not designed solely to drive the King ESL, but the King was used in the voicing of the Phi 200. Improvements to a VAC design are only accepted if it sounds better with some or all speakers tested and worse with none.
 
VAC Fact: The voicing process may take Kevin and VAC engineers up to 1,000 person-hours in some cases; that’s beyond the time taken to get the amps to measure well on the bench! If Kevin does not approve the sound of an individual component (he listens to each one), it does not ship. Production of certain models has ceased at times for up to two months while tracking down a variance in vendor’s products, such as wires or capacitors.
 
VAC Fact: The voicing process of the Phi 200 was thought to be done until a pair of Zingali horn speakers were hooked up. Through the Zingali, the circuit sounded bright, yet soft, which called for an adjustment to increase the control and precision of the top octave. The cure was affected, but the change was completely inaudible on a pair of Thiel speakers.
 
VAC Fact: Kevin’s opinion of Class D amplification, “… we have neither seen nor heard anything in theory or in practice to suggest that Class D would be a good idea with regard to sound quality.”
 
VAC Fact: At the upcoming 2011 Consumer Electronics Show (CES) in Las Vegas, VAC will introduce the Phi 200i, an integrated amplifier mechanically like the Phi 300.1a, but with 110 wpc. It is designed to overcome many of the shortcomings of integrated amps. It uses two separate power transformers, one for the pre and the other for the power amplifier. It will include a genuine line stage as opposed to being an amp with a volume control, and phono stage. Kevin says, “It should be roughly equivalent to the combination of Renaissance MkIII Preamplifier and Phi 200 Amplifier.” Also on the horizon is the Sigma 160i integrated amplifier (see, another Greek letter name) which will look similar to the Phi 200 and cost approximately $9,900 (NZ$15,495 incl GST).
 
Get a listening VACcination
Got the jitters, a bad case of Audiophilia Nervosa? Can’t seem to find that perfect sound? Nothing seems real enough sounding to you? Doctor Doug says get a shot of VAC equipment and you’ll start feeling better. I certainly feel better every time I use VAC gear in the systems I build. I do mean every time. If there has been one amplifier which has never failed me when reaching for top shelf sound, it is the Phi 200.
 
I already stated in the Signature Preamplifier MkII review that the preamp saves other brands of amps from poor performance; it literally preserves them from ignominy. I can say the same of the Phi 200. Of all the amplifiers my hands have touched thus far reviewing – you can check the list of my reviews – the Phi 200 is the amplifier I would keep. Following are the reasons, based on my listening impressions.
 
VAC equipment has an uncharacteristically big, beautiful sound. I first heard the Phi 200 with the King ESL. Am I glad I did, because there is a possibility that under show conditions hearing it with a different amp I may have dismissed it – a huge mistake. The King is extraordinarily good, and has sounded better with the Phi 200 than with any other amps I have used. I have used some good solid-state and hybrid amps with the king – Cambridge Audio Azur 840W amps in Bi-amp configuration, Pathos Classic One MkIII hybrids in Mono mode at 270wpc into 4 Ohms, a pair of Moscode 402Au, and the Einstein “The Light In The Dark”, as well as some others currently under review. I have had the Phi 200 on loan long enough to have compared it in more head-to-head listening tests with other amps than any other amp I have reviewed. I have heard the Phi 200 on about as many speaker systems as Kevin has for voicing. The conclusion is clear: the balance of power, fullness, and correctness is unparalleled. The King sounds good with one Phi 200, but is inspirational with two of them in Mono mode.
 
Recently a local dealer for VAC instruments came to my home twice to hear the King. The first time he heard it with solid-state amplification and thought it was nice. Prior to his return I told him, “Just wait until you hear the King with two Phi 200’s!” This time he brought his own discs, and this time he left with the phone number of Roger DuNaier at Performance Devices, because he had made up his mind he needed to carry the King as his ESL. It speaks well of an amp when a dealer is swayed to carry a line of speakers from hearing a system which has only had it inserted! The Phi 200 is that good. I know any time I am not hearing sound which is up to my ever escalating standards I can put the Phi 200’s in the rig and get that which I seek.
 
Rodrigo Y Gabriela
If you haven’t had opportunity to look up an incendiary guitar duo named Rodrigo Y Gabriela, I encourage you to do so. This fast paced, punch-packing acoustic guitar pairing has become a favorite for listening as well as conducting demos of equipment. I highly recommend their Live in Japan disc.
 
One track, named “FOC” – I’m almost afraid to know the meaning – has an extended percussion segment with the bodies of the guitars used to thump and pound out the driving rhythm. The clarity and depth of the Phi 200 is exemplary, allowing one to hear much further into the acoustic space of the venue than with the aforementioned amps. The Phi 200 seems to harbor more power than its specified rating. When the guitar is slapped one hears what I heard in the live performance, a powerful wallop, a percussive slam from the close microphone positioning, and a highly amplified signal all reverberating off the auditorium’s wall.
 
One does not hear from the VAC what most amps do to Rodrigo’s picking and plucking, a thinning out of the wiry notes. While initially such thinness is quite noticeable and seems captivating as “detail”, after a short while it becomes irritatingly brittle sounding. At first blush the VAC components may seem laid back, too reticent. But when listening to such intense playing and at higher levels for several minutes, much less a half hour, that more controlled expression of the string’s snap is very welcome as fatigue does not set in. In fact, fatigue never set in with these amps.
 
It reminds me of the lack of strain on the eye looking at a sunset versus summer midday sunlight. The sheer brightness of the sun causes one to squint, to filter out some photons crashing into the iris, but the late afternoon sky is much more forgiving. In the same way, some amps hand the music to your ear “bright and white”, strong and clear but in such a churlish manner that the ear wants to “squint”. Not so with the VAC, as you can put on truly harsh tunes and have the ear wrenching audacity of it ameliorated.
 
I have a couple of nastier test pieces for systems, ones which most systems even at shows fail miserably. One is Lenny Kravitz’s “American Woman”, and another is Apocalyptica’s “Enter the Sandman”. Kravitz plays with the vocals toward the end of the song, distorting his voice out of all proportion to decency. Even on good rigs he sounds so awful that I can usually not listen to the end; he comes across as a robot with a bullhorn singing. As for Apocalyptica, a truly hard driving band with three classically trained cellists and a drummer, I have not much good to say for the music; I just like getting a kick out of seeing if a system can handle it. The strings screech wretchedly, just the kind of effect needed to test the limits of a stereo’s top-end performance!
 
Watch out if you tee up either one of these to hit, because your system is likely to slice and send them sailing “out of bounds”. Only a handful of times have I avoided the cringe-factor when hearing these pieces and one of the only systems to handle them with any kind of aplomb was in my room with the Phi 200. The mollifying effect of the Phi 200 is to make these abominations sound like music. I can actually listen through to the end and pretend like I appreciate it. Anything less than fantastic amplification and these pieces get an automatic penalty; stop the music and move to the next artist.
 
Once I have the Signature Preamplifier MkII and Phi 200 dialed-in, I do not recall any piece I have terminated due to over-aggressiveness. On the other hand, I do recall replaying favorite pieces successively in an attempt to instill more of the mood, the aura, the loveliness of it. I usually want to move ahead, go on to the next experience, but I may repeat a performance when the Phi 200 is in the rig and feel it’s no waste of time.
 
More Stringent Criteria
Increasingly, as I age I am not interested in brightness, or “definition at all costs”. When I was younger I was willing to put up with such antics, but no longer. I have not capitulated on the demand for detail and definition. On the contrary, I demand them more than ever, but with the condition that they must be musically appropriate to the genre and recording. There are only two situations in use of power amps where I can say that both of these demands have been met to my satisfaction. One is with a trio of Coda CS amplifiers (under review) operating the Legacy Audio Whisper DSW in fully active crossover mode, a setup which gives a very unfair advantage to a solid-state amp.
 
The other is the more traditional loudspeaker of either the King Sound King or the Whisper DSW operating in passive crossover mode, powered by the pair of Phi 200 amps. That this setup can compete with a six-channel fully active crossover system is a testament to the authority and quality of the Phi 200. The best part is that the authority and quality is transferrable to any dynamic, full-range ESL or horn speaker system.
 
No kidding around
If you like upbeat vocals, you might want to check out Bobby McFerrin’s VOCAbuLarieS, in which he employs more than fifty singers weaving them into his energized African-inspired choral and solo works. The first track, “Baby”, is infectiously repetitive and upbeat as it brings to mind the runabout antics of a small child.
 
In comparison with the Einstein “The Light In The Dark”, the closest amp in quality to the VAC of those I have used, I found the Phi 200 to offer more heft in the bass singers’ voices, a touch more smoothness in blending all the singers and comparable clarity. When using the Ayon CD-5 as source with its internal preamplifier’s selectable gain setting at MID (6V), vocals sounded as if emanating from oversized heads. This effect was compounded when hearing it through the King, as ESLs tend to expand the center image anyway. With use of the 1-2 Ohm posts on the King and the GAIN of the CD-5 set to LOW (4V), the singers became more life sized and properly weighted. There is a terrific amount of flexibility offered by pairing higher-output sources like the CD-5 with the Phi 200, but you will want to watch out using output over 4V as it will likely begin to “inflate” the amp’s performance. Some people may adore that big-as-the-room sound, but others will want to rein it in.
 
The VAC sound is audio-writ large but properly proportioned; it is elegant, opulent and ebullient. The vastness and spatiality of the soundstage with the Phi 200 is quite surprising when heard for the first time. You may have heard many amps with differing power resources, and different levels of clarity. If you have worked primarily with solid-state amps, you likely have not heard the expansiveness a fine tube amp can bring to a system.
 
Perfect Storm System
The Phi 200 is a natural winner when it comes to symphonic and chamber music. The flush tonal quality of natural instruments created by the Phi 200 enlivens a score. I recently picked up James Horner’s soundtrack for The Perfect Storm, a Deadliest Catch-like account of the Andrea Gail, a long line fishing vessel doomed at sea in one of the worst meteorological disasters to hit the eastern seaboard in a century. As an aside I recommend not only the movie but also the book; so much more of the human element comes through in the painstaking recounting, including a morbid description of what likely the men onboard were undergoing as their ship foundered, sank, and they drowned. The grandeur and gruesomeness of commercial fishing off the Grand Banks is compelling to the spirit of those who labor with their hands as well as those who cheer people finding themselves on the short side of the odds.
 
I like to see what an amp can do with powerfully orchestrated pieces. In The Perfect Storm soundtrack, the periodic wave action flow to the music captures the vicissitudes of the sea. The Phi 200 does not drain the life from the piece, as some amps do. It is easy to be at sea, visualizing the images from the movie; with the VAC I’m not distracted by a question of how that particular horn sounds or why a drum does not seem deep enough. All is rendered with tonal correctness and proper weighting, so I can relax and immerse myself in the moment.
 
Especially rewarding are the tracks “The Decision To Turn Around” and “Rogue Wave”, both of which have attacks of low register horns and tympani. The Phi 200 is exemplary in capturing the surge of the symphony as it crashes in crescendo, emulating the killer waves of the ferocious hurricane. In “Rogue Wave” the last, sustained trumpet blasts speak of panic, heroism – anything that grasps at another moment of hope. The swirling strings and building wall of drums tear at the heart as one conceives the wall of watery grave about to engulf the hapless crew. Following the pounding of the vessel and its sinking an eerie silence ensues, and inevitably the ebb and flow of the ocean’s sub-surface melody is enjoined once again. The humans were no match and will not be remembered by the sea, but washed from memory. The Phi 200 captures the terrific undertow of the score, pulling the ear downward toward the depths in an overwhelmingly compelling fashion.
 
Ideal for any speaker
My experience with the Phi 200 is that I can be assured that no matter which loudspeaker I put into the rig I’ll get top quality sound. About two months ago another manufacturer was visiting for a couple days in order to establish a speaker for review. The VAC components were in use, so it was not surprising to me that I found out later he had enthused to a cable manufacturer that my rig was special. I hadn’t even gotten a chance to work with the speaker for weeks to dial it in. Already with the “first run” the system was charming; the VAC gear was working its magic.
 
I find it difficult to determine which system I prefer, the big panels or the big dynamic hybrids. The Phi 200 in mono drives them both with authority and acuity. With most amps I have to work hard to get a sustainable level of palpability, of convincingly true-to-life sound. Not with the Phi 200. In a matter of one evening I can dial it in to find a viscerally moving experience.
 
Here is a secret about how I build high-end systems. I do not spend weeks or months sitting around pondering their sound. If something does not sound right I act directly and immediately to make the effected repair. Consider that industry leaders head to a show and set up in a room from scratch. They do not have weeks or months to futz with sound. They must get it right as best they can, many times literally overnight. Some are definitely better than others, but most do a commendable job given the schedule and circumstances.
 
I have found that it’s counter-productive to waste weeks and months seeking an optimum sound when the ear senses an obvious defect. If a system doesn’t sound good to me I do not wait on it, I change something! For this reason I keep two or three types of cables on hand in order to tune rigs. There are tens of thousands of permutations available for systems. Why should I waste weeks or months of my life with a so-so sound when I can potentially improve it immediately? The longer I have been in the game the less patience I have to adopt a “wait-and-see” attitude. I have a firm grasp of my electronics collection and media collection, as well as how I demand it to sound. If it’s not where I want it to be, I’m not about to spend weeks suffering its insufficiency. Something’s getting reworked! Of course, finances can slow down the process, but if finances are not hindering and the rig doesn’t sound right, it’s not going to stay that way for long.
 
Imagine the number of audiophiles who sit in discontent at their rig’s sound, pining for improvement! How many hope that it will improve on its own with weeks or even months? If you don’t want to spend the majority of your time as a discontented audiophile, get to work! I spent far too many years hoping for incremental improvements, so I want to encourage those who are frustrated not to accept waiting and doing nothing. If there is an annoying aspect to the system, change a power cord or two, or try a different speaker placement, or put a pillow behind the speaker to test if room treatments might help. Your ears will tell you if you are going in the right direction, just as your eyes tell you when you see a beautiful person. Influence change for improvement rather than be a victim of inaction.
 
However, once a very pleasing sound has been found I slow the process down every bit as dramatically. The ear will tell you when it hears something good. When my ear sends the signal, “Ah! I really like this sound,” I halt the system reconfigurations and spend time enjoying. More often than not the system will remain fixed for some time and I will authentically thrill to the sound of it for weeks. It’s so much better than leaving niggling concerns about the sound unaddressed. If I get my concerns about the sound dealt with up front, I find myself much more content with the system for longer periods of time such that I become reluctant to disassemble the rig!
 
When I’m in “Reconfiguration Mode”, usually cables are the first to be reworked, partly because they can be incrementally changed, and partly because they are easiest to work with physically. If I’m confident of the source’s quality then the next thing to be considered for change is the amp. But never the VAC Phi 200. I have moved it in and out of the rigs I have built enough times that I have heard the devastation resulting from its removal. It has become an “anchor component” which has proven itself the best option no matter which team of components I assemble. Inevitably, it is re-inserted into the system to restore much needed vitality. When another amp’s review work has been concluded, out it goes and in goes the Phi 200. I have preferred over the months to build rigs around it rather than work without it. This confirms Kevin’s voicing process, whereby the amp is conditioned to be compatible with a wide range of speakers.
 
Thus it was that recently when I put the Whisper DSW back into the rig I instinctively reached for the Phi 200’s, no matter the other components and cables. I keep an updated exact system list from power cord for the source to speakers for the “Best Rig” with every speaker system. I could have simply recreated my previous best rig. However, I decided to fly solo and rework the cabling again. In the span of two hours and four partial cable changes, I was content. The results obtained are often so right, so spot-on that I leave it that way for weeks until another review priority forces change. As amps have come and gone, the Phi 200 has remained and if I had the means financially they would remain permanently. Their quality, reliability and unimpeachable sound earn them a resounding recommendation.
 
In conclusion I leave you with two more VAC Facts.
Firstly, Kevin is also interested in the quality of the discovery and reporting in regards to his products as they are used in real-life systems. He is not so concerned with analyzing specifications to death, but rather what works in terms of obtaining the best sound. This review is my most comprehensive to date in terms of an amplifier’s use with other components. I subjected the Phi 200 to more sources, preamps, cables and speakers – systems – than any previously reviewed piece. It yielded top-quality sound with a large body of available components.
 
Secondly, with CES around the corner and enthusiasts hearing his components, I suspect Kevin is about to get a lot busier. If you like what you hear and seek a VAC instrument, be patient. Your patience will be well rewarded. Kevin’s concern is producing a quality instrument above all. You are paying him for the best amp he can build, and he’s going to make sure you get it. That is why he’s going to listen to it before it ships.
 
Manufacturer’s comment:
Thank you for the thorough and thoughtful review of the VAC Phi 200, as well as for the courtesy and professionalism always shown us by everyone at Dagogo.
 
A quick note about the VAC / KingSound demonstration at the inaugural 2010 California Audio Show. After discussions with the dealer, Bob Kehn of Audio Image, who presented the room, it was determined that the King’s panels likely were not fully charged most or all of the time, which results in reduced sensitivity and premature clipping of the panels themselves. The problem was that the speakers were left unplugged when the alternate Magico speakers were being demonstrated. Normally I would not have thought of this, but we experienced a similar issue during setup at Axpona; the speakers had to be plugged in (and unplayed) for several hours before they would play normally. Clarity about this is important, as we would not want the King’s to get a reputation for being difficult to drive, nor would we want the stereo Phi 200 to be viewed as marginal for the task!
 
To clarify the bias setting of the output tubes, the proper procedure is performed without music playing, as initially stated in the review. Once the proper settings have been achieved, in normal operation one will notice that the LEDs will be dark when no music is playing, and will light ‘with the beat’ as music is played. However, this is not part of the adjustment procedure, and there is no need to select a particular kind of music, etc.
 
Thank you again for taking the time to review the VAC Phi 200. We count it a privilege.
 
Kind regards,
 
Kevin Hayes / VAC
 
the Phi 200 proved superior in resolution, inner detail, imaging, soundstaging, speed, and pace, rhythm, and timing (PRaT). Its top-end and midrange definition, articulation, and dynamics were amazing.
. . . Garrett Hongo

 From the start, the Phi 200 exhibited terrific dynamism and extension, an unmistakable speediness, and tightly focused imaging. The "jump factor" was tremendous. The VAC's timing was especially notable: cues and attack transients from tight studio bands, orchestras, and chamber musicians fell not blithely into place, but sprang from the speakers like panthers quick and lithe.  

Kevin Hayes has come up with something very special in the Phi 200: a tubed stereo amplifier with the speed, grip, and top-end extension of solid-state, yet with the flow, sparkle, and treble sweetness of tubes. At its listed retail price it's a serious high-end investment, but it deserves to be considered by anyone who's interested in the cutting edge of audio engineering. It's a cliché to say that the sounds of the best tubed and solid-state electronics are now closer to each other than ever before, especially if those sounds have lost something of the magic of vintage gear, but the VAC Phi 200 has a magic all its own -- there's a commanding ghost in this machine that sings clearly, cleanly, and with potent vitality. 

Recent Western literary theory makes a distinction between the author of a book and its writer. The author is the ephemeral entity conjured as the consciousness within a given work -- a novel, say -- while its writer is the actual person who wrote it. The essential difference is that the writer has a life outside the scope of the book -- s/he eats, sleeps, messes around, plays with stereos, etc. The author resides only in the work itself, spectrally, a being conjured by the words of the text -- limited in existence, only a voice or a presence behind the words. There might be a parallel to this in hi-fi: an audio component not only has its "writer" -- the designer who goes on living life, designing other components, showing up at Consumer Electronics Shows, racing balloons in Kansas, shredding the break on the Inside Reef at Makaha -- but also its "author," the virtual voice within the machine. 
 
In this sense, the "writer" of the Valve Amplification Company is Kevin Hayes, president and chief designer of fine audio electronics since VAC's inception. I have met Hayes, exchanged jokes with him at audio shows, and spoken at length with him on the phone. He is definitely a personage. And yet, each VAC component has also its "author," a specific character conjured in the sound of the individual piece of gear itself, a kind of spirit in the sound. If we apply this philosophic notion of split entities to audio, it runs counter to the traditional audiophile view that identifies a particular "house sound" throughout a given line of electronics, insisting that all components produced by a company share, by design, a common character. 
 
My own thinking about VAC electronics had ascribed to them a shared house sound, a constancy of voice (or single authorial presence) that was warm, somewhat sumptuous, and emphasized sensuousness over precision. But to my ears, the Phi 200 stereo amplifier ($9990 USD) is something quite distinct from this. It breaks with my own prior assumptions about any "house" sound VAC gear might be said to possess. 
 
The description of the Phi line of amps on VAC's website boldly compares their sound with that normally associated with solid-state: "The Phi amplifiers produce the areas of beauty typically associated with good vacuum tube designs, but also go well beyond this, producing bass impact, speed, and dynamics that have converted many adherents of solid-state design." And, a bit further down the page: "You will hear the punch and control normally associated with solid-state amplifiers. . . ." 
 
I heartily agree. Kevin Hayes has created something startling in the Phi 200, his latest tubed amplifier. The authorial voice that emerges from it produces a quality of precision -- in imaging, microdetail, microdynamics, transient speed, treble extension, and bass grip, all within a generous soundstage -- that many think is possible only with solid-state designs. This ain't your Daddy's Oldsmobile, people. 
 
Description 
 
The Phi 200 is a 100Wpc power amplifier with speaker taps for loads of 1-2, 2-4, and 4-8 ohms. Its tube complement consists of four KT88s and four 6SN7s. Though it can be easily converted for use as a 200W monoblock via a mode switch on the rear panel, I never used it that way. Fully balanced in its circuitry, the Phi 200 has both XLR and RCA input modes, and its gains are a claimed 36dB single-ended or 30dB balanced. The input and driver stages are the class-A, direct-coupled, low-mu triode circuits originally developed for VAC's Phi 300 amp (150Wpc). The bandwidth claims are impressive: 13Hz-70kHz power bandwidth and a frequency response of 4Hz-75kHz. 
 
The Phi 200 is large -- 17.8"W x 8.75"H x 17.8"D -- and weighs 90 pounds. Most of its weight is in the rear, where the massive, custom-wound transformers are mounted. The nonmagnetic chassis is 2.4mm thick and comes in an impressive black powdercoat. The 9mm-thick faceplate comes in black lacquer with gold flecks, or silver lacquer with the chassis in contrasting black powdercoat. The VAC logo, on a handsome piece of recessed glass on the front panel, is backlit in blue when the amp is switched on. All in all, the look is clean, post-utilitarian, and very attractive.
 
Design 
 
The Phi 200, introduced at the 2008 Rocky Mountain Audio Fest, was developed from the Phi 300 stereo amplifier (now the Phi 300.1a in current iteration), which Kevin Hayes had created in 2006. "It brings the Phi technology to a price point accessible to more people," he told me by phone. 
 
When I asked what the Phi technology is, precisely, Hayes explained that it’s a new front-end and driver-circuit topology he'd developed from the high-mu paraphase circuit employed in his first amps, the PA-45 and PA-90 monoblocks from 1990. Paraphase refers to the type of phase inverter used in the front-end with single-ended signals, and differs from the Williamson front-end circuit used in VAC's PA-80/80 and PA-100/100 stereo amps from later in the '90s. Whereas the Williamson front-end circuit used a "cathodyne" phase splitter that is capacitively coupled to the driver, and the paraphase circuit in the earliest VAC amps used high-mu triodes, also capacitively coupled to the driver stage, the new Phi paraphase circuit uses low-mu triodes at the input and driver stages and eliminates the capacitors for direct coupling to the drivers. In balanced mode, there are no coupling capacitors in the input and driver stages, and, even in single-ended mode, the input circuit has only a "half-capacitive" stage -- still fairly direct, compared to earlier VAC designs. 
 
What this means for the listener, Hayes said, is that Phi amps are much faster than VAC's first paraphase mono amps and Williamson-derived stereo amps, and hopefully produce more vividness and energy without giving up anything in terms of liquidity, nuance, and soundstaging. 
 
What Hayes didn't expect was an improvement in bass performance. "Some hear a distinct increase of bass control and articulation," he said. But what was most interesting was that the new Phi circuits didn't change the basic match between the output stage and the speakers, where many have assumed tube amps lose their grip on the bass. "It is assumed that the damping factor has to be high," Hayes explained, "but the new circuit in the Phi 300 (and subsequent 300.1 and 300.1a) and Phi 200 didn't change the damping factor one bit." 
 
Hmmmm, I thought. O brave new world that has such amps in't! 
 
Setup and operation 
 
The Phi 200 arrived in a large (24.5" x 12.75" x 13"), sturdy cardboard box, nested top and bottom in thick, fitted blocks of urethane foam. Inside were eight boxed vacuum tubes -- four Shuguang KT88-SCs and four Shuguang 6SN7s -- each tested by VAC and carefully labeled for a corresponding socket position on the amp's top deck (even the center pins of the power tubes are so marked). In a nice touch, the amp's faceplate was covered in a soft polishing cloth held in place by a cat's cradle of rubber bands. There were also a stock power cord (which I did not use), a yellow ochre plastic bias tool (marked Vishay Spectrol), and an 8.5" x 11", 15-page owner's manual that meticulously describes setup, tube position, and operation. The warranty is two years, parts and labor, excluding tubes. 
 
I seated the tubes in their sockets, carefully matching each to its designated position on the chassis, then hooked up the cables. The Phi 200's connectors are mounted on the top of the chassis at the rear, along a narrow shelf behind the power and output transformers. This proved very convenient for attaching the spades of my speaker wires and RCA and XLR interconnects (I alternated my use of the latter). 
 
Biasing the tubes was a cinch -- the bias lights are in a row behind the output tubes, and each glows red or orange or green, depending on the setting. With the amp on and no music playing, you insert the blade of the bias tool (or a very thin-bladed, flathead screwdriver) in the numbered hole in the chassis that corresponds to a particular tube, fit it into the slot in the head of the bias screw inside that hole, and turn the screw. The bias light will go from red through orange; when it has just turned green, the setting is correct. The procedure was familiar to me; it's pretty much been the bias routine for VAC amps for over 15 years. 
 
Switching from balanced to single-ended operation is similarly easy. Each channel has a set switch just to the side of each input tube. The forward setting is labeled Singled Ended, the rear setting Balanced. Just make sure both channels are set correctly and you're good to go. The VAC Phi 200 is turned on and off with a switch on the right of the faceplate -- much more convenient than amps with power switches on the back! Finally, the Phi 200 does not invert absolute phase. 
 
Throughout the review period I used various combinations of cables, including a couple of very reputable, high-end brands, and both XLR and RCA interconnects, before settling on my reference Verbatim speaker cables, Verbatim RCA interconnects, and Cardas Golden Reference AC cord. I also tried two different preamplifiers: a deHavilland Mercury 3 and a VAC Renaissance 3. The Phi 200 sounded best run single-ended via its 4-8-ohm taps (my Von Schweikert VR5 HSE speakers are rated at 91dB and 6 ohms). It performed very well with both preamps, though most of my listening was done with the VAC Renaissance 3. With the stock and various NOS input and driver tubes I tried, in both balanced and single-ended modes, the amp operated smoothly and without a hitch throughout the review period. Break-in did seem to take a while, likely due to the transformers needing serious run-in before they settled. I ran the amp for over 200 hours before taking any listening notes. 
 
Sound 
 
From the start, the Phi 200 exhibited terrific dynamism and extension, an unmistakable speediness, and tightly focused imaging. The "jump factor" was tremendous. The VAC's timing was especially notable: cues and attack transients from tight studio bands, orchestras, and chamber musicians fell not blithely into place, but sprang from the speakers like panthers quick and lithe. 
 
The imaging, speed, and soundstaging were spectacular with "Smooth," from Carlos Santana's Supernatural (CD, Arista 07822-19080-2). Instruments extended far into the room, my speakers disappeared, and the band was spread horizontally across a wide soundstage as Rob Thomas's electronically manipulated and sometimes deliberately artificially dry voice dodged annoyingly here and there in the soundfield. Other than that studio trick, the sound was clear and extremely liquid, the Phi 200 providing the best soundstage I've ever heard in my smallish (12'W x 16'L x 8.5'H) listening room. The sound was also extraordinarily clean, with each instrument in its own defined airspace. These aren't things I usually crave in my listening, but I had to take notice of every excellence provided by the Phi 200: clear, sometimes crystalline timbres in the highs, tremendous drive and detail, and lots of timbral separation among instruments. "Like solid-state," my notes say, "but with more liquidity, more sensuousness note to note" -- and yet no tubey warmth, confirming almost completely the claims made on VAC's webpage. 
 
From Eric Clapton's famous Unplugged (CD, Reprise 45024-2) I got consistently tight bass, great pitch definition, and a supremely clean sound. My notes: "Clarity, clarity, clarity." From my usual electronics I heard greatly improved transient snap, microdynamics, and drive. Voices and instruments were more sharply defined, and small details I hadn't heard before, such as the squeak of fingers on wound guitar strings, popped in and out of the mix. Female backing vocals, the buzz of Clapton's bottle slide on the steel-wound strings, and the soft whump of a washtub bass -- all bubbled sweetly into the soundfield. 
 
Conventionally, you'd think that a sound as detailed as I'm writing about would have produced an overall impression of an "analytical," even a clinical sound, but that was far from the case -- what resulted was an even stronger connection to the music. I must have listened to "Tears in Heaven" over a hundred times through various systems over the years, but hearing it with the Phi 200, all the nuances -- Clapton's marvelously percussive nylon-stringed guitar intertwining as intricately as bougainvillea on a bamboo lattice with Andy Fairweather Low's tasteful accompaniment on his own nylon-stringed guitar, Chuck Leavell's mournful synthesizer, Nathan East's tasteful and at times melodic plucking of the bass, the subtle background singing of Katie Kissoon and Tessa Niles, the regret-tinged timbre of Clapton's lead vocal -- came together in what seemed a performance as close to "live" as I've ever heard. This noble dirge of a song, its humble prayer, and its tragic story affected me as never before. It was emotional. 
 
But in those first few weeks I also struggled to sort the character of the Phi 200 from what turned out to be high-frequency distortion picked up somewhere and amplified by the system. The highs in classical music and female voices seemed peakish, even edgy at times, and violins and soprano voices were often oddly ragged. I heard a top-end tizz -- a very fine hash -- that translated into a kind of grit in the treble range. Trying a few different cabling combinations revealed the problem to be one of airborne vibration. My right speaker is right next to my audio rack, and the tops of the CD player and preamp naturally pick up a lot of airborne energy. This normally isn't a problem with my reference monoblock amps, the tubed deHavilland KE50As, or other amps, but the Phi 200 moved so much more air, proved so dynamic and fulsome in top-end extension, that it energized my listening room to the point that I heard problems. 
 
At first, I placed a few ziplock bags filled with rice -- my do-it-myself damping pillows -- atop the preamp. This did the trick, however inelegantly. Later, via Audiogon, I discovered some handsome dampers of solid brass made by edenSound. These chamfered discs, called FatBoys ($39 each), are 3" in diameter and about 1" tall, with Elastomer on the contact end to protect your gear, and completely calmed the excess energy on the preamp chassis. I continued to use the bags of rice on my CD player, and eventually tucked them inside some black cotton Tibetan shoulder purses ($7 each) I found at my local singing-bowl store. I liked that they were decorated with the mandala of the I Ching. 
 
Those problems solved, the Phi 200 provided such tremendous clarity that it made me curious about period instruments and the rapid vocal ornamentations in music from the Italian Baroque, particularly the compositions of Vivaldi. I wanted to pit the amp's speed against its clarity, its ability to keep up with virtuosic performances on multiple instruments, their harmonies and distinct timbres, and hear if it could reproduce these without losing significant detail and thus becoming more impressionistic than precise. 
 
I played several different Vivaldi recordings in my collection -- Fabio Biondi and Europa Galante, the Venice Baroque Orchestra with Giuliano Carmignola, Rachel Podger's La Stravaganza, and several of the operas -- but in the end focused on soprano Sandrine Piau's In Furore: Laudite Pueri e Concerti Sacri, with the Accademia Bizantina directed by Ottavio Donatone (CD, Naïve OP 30416), particularly Vivaldi's motet In furore iustissimae irae for soprano, two violins, and viola e basso. The Phi 200 proved superb with period strings, rendering a fast, clean sound without glare, etch, or that notorious sourness that many complain such instruments have when played without vibrato. The amp captured all the vivaciousness and warp speed of play of the baroque ensemble. Especially satisfying were the overtones and harmonics of the instruments being woven together in an involving musical tapestry. I was able to consider the complexities of tone not only of each instrument, but also the superadded richness of tonalities and drive that emerged from each thematic run of the ensemble's playing. And Piau's singing in the closing Alleluia was a combination of percussive, pulsating trilling and gorgeously rapid roulades. As a test of the amp's agility, speed, and timbral accuracy, Vivaldi and a virtuosic soprano presented no problem. 
 
But for all the pleasures of the Phi 200's speed and accuracy, I wondered about midrange sweetness, and a kind of tonal richness I call saturation, along with the tonal complexity I'd already heard -- the plumminess of a single note, and gravitas vs. vivacity. For this, I listened to J.S. Bach's Suites for Solo Cello in a new digital recording by Jean-Guihen Queyras (CD, Harmonia Mundi 901970.71), and here the contribution of the VAC Phi 200 to my system's sound made for a revelatory and pleasurable experience. In Allemande, the second movement of Suite 4, Queyras's cello sounded rich, resonant, resolute, and made for soaring melodic lines. The sound was big, sonorous, and room-filling, sometimes jumping out of the speakers in a startling way, but pleasing in all its warmth and musicality. The supreme clarity of the sound captured how precise and articulate Queyras's fingering is, how sensuously in time with his bowing. I could hear the cello's body, its depth of resonance and generous warmth, particularly when it picked up the vibrations of the lower strings to resonate in the wood, each note full of microtones and natural-sounding harmonics. Queyras's patient, even playing was never rushed, never ornate with flourishes, but lovingly pensive -- like musical thoughts, completely sensical and yet emotional as well. I could hear his short intakes of breath in rhythm with the beginnings of extended sequences of bowing. The long decay of the cello's resonance was also completely audible, even after Queyras had stopped bowing -- a precious piece of performance detail heard in live concerts but often missing from recordings. It was the best I've ever heard this recording sound. Several nights running, I listened to these two CDs many times through, deep into the early-morning hours, for the sheer enjoyment of their plush yet supremely articulate midrange capably rendered by the Phi 200. 
 
Not to ignore the VAC amp's reproduction of vinyl recordings, I listened to lots of LPs -- jazz, piano, blues, and symphonic music. These analog recordings exhibited a character in keeping with what the Phi 200 revealed of digital recordings. I played a reissue of Holst's The Planets, with Zubin Mehta conducting the Los Angeles Philharmonic (180gm LP, Decca/Speakers Corner SXL 6529). The first movement, Mars, the Bringer of War, presented a fine and articulate timbral palette. Exquisitely rendered were the tonal contrasts between the solo trumpet and horn fanfares, and between the violin section and the piccolo and flutes. Treble extension was very fine and sophisticated, but when the drumstrokes, trombones, tubas, and bass viols are all played at the climax of a crescendo, I missed some of the bottom-end slam and fullness of my reference deHavilland KE50A monoblocks. Yet with the Phi 200, each drumstroke and bass note seemed more contained in the midbass, each sound tighter, more taut and controlled, with perhaps better pitch definition, if a shade lesser in sheer impact. Again, the VAC amp had an easy time precisely distinguishing among the varied timbres of violins, horns, oboes, flutes, and piccolo. There were gorgeous contrasts of the timpani with glockenspiel, flute, harp, bassoon in Mercury, and lots of the varied tonal colors of strings, horns, and woodwinds in Jupiter. I could easily tell the trombones from the French horns. 
 
I compared the VAC Phi 200 with three different power amplifiers: my venerable VAC PA-80/80 (80Wpc; discontinued), my reference deHavilland KE50A tube monoblocks 40W;  and a pair of Herron Audio M1 solid-state monoblocks (150W, . In each case, with the same recordings, the Phi 200 proved superior in resolution, inner detail, imaging, soundstaging, speed, and pace, rhythm, and timing (PRaT). Its top-end and midrange definition, articulation, and dynamics were amazing. The VAC PA-80/80 has a much softer sound, a warmer and more prominent midrange. The deHavilland KE50As are bloomier, giving the notes more body and longer decay, and have a fuller bottom end. But the deHavillands are more Impressionist in approach, more enveloping and perhaps more dramatic; the Phi 200 was more precise. Finally, the solid-state Herron M1s somehow sounded more tube-like than the Phi 200 -- mellower, softer in attack, closer in character to the deHavillands than the Phi 200. All in all, compared to the amps in my collection, the Phi 200 seemed a new beast altogether -- unbeatable in soundstaging and inner detail, wondrous with imaging, speedy in attack, blessed with superb top-end clarity and sparkle and a gorgeous midrange, and exerting a powerful grip on the music's timing and the midbass. 
 
Conclusions 
 
Kevin Hayes has come up with something very special in the Phi 200: a tubed stereo amplifier with the speed, grip, and top-end extension of solid-state, yet with the flow, sparkle, and treble sweetness of tubes. At its listed retail price it's a serious high-end investment, but it deserves to be considered by anyone who's interested in the cutting edge of audio engineering. It's a cliché to say that the sounds of the best tubed and solid-state electronics are now closer to each other than ever before, especially if those sounds have lost something of the magic of vintage gear, but the VAC Phi 200 has a magic all its own -- there's a commanding ghost in this machine that sings clearly, cleanly, and with potent vitality. 
 
. . . Garrett Hongo