Doug Schroeder on a pair of the $5,500 PATHOS CLASSIC ONE MKIII: how his fever got higher
December, 2007
Introduction to Classic One MKIII Review: Having been an owner of the bridged Pathos Classic One MkII tube hybrid integrateds, I felt compelled to write of their virtues. The segment of the review dealing with the MkII version of this amp was a labor of love written approximately one year ago. I enjoy the Classic One and want its unique configuration capabilities known to wider circles of audiophiles.
This review has been held for some time prior to publication, as I have now acquired the MKIII version of these amps. In an addendum, I shall detail the differences between the two versions. Please note that small aesthetic and operational differences exist between these two versions; these differences are summarized in the above comments from Pathos. However, these differences may be important, i.e. color options, so if you are a potential buyer I urge you to visit the website, www.pathosacoustics.com, to familiarize yourself with the MKIII.
There’s no mistaking a classy-looking component when one sees it. People who enter my home theater, where twin Pathos Acoustics Classic One MkII tube hybrid integrated amps reside, immediately notice them as being in an entirely different class of component than the usual box and faceplate. Audiophiles (I might venture a guess here, based on familiarity with the topic on electronic forums as well as my own objectives) typically care more about the sound of the equipment than its looks. Not all, but a majority might sacrifice appearance for the superlative sound of a component. Rightly so; if looks are predominant, there are some nifty speaker systems available through The Sharper Image that might satisfy, but have limited value to the audiophile.
The Classic One MkII IS a classic in all respects of its design, from the selection of the materials aesthetically, to the sonic performance. Physically, one unit is noticeable, but two are utterly unavoidable! Every person who enters my listening room is immediately drawn to them and ask the same question, “What are those?” In the process, they bypass speakers, at two times the retail value of both Pathos amps, which are every bit as acoustically impressive and contain ingenious technical aspects to their construction and design but are not as visually stunning. The Classic One MkII is an “attention getter.” Frankly, I must admit, it’s great fun to own equipment with a high “Wow” factor! I enjoy telling people, “Those are my Italian tube hybrid integrated amps!”
To obtain technical information on the amp, which doesn’t appear in the owner’s manual, one must look to the website – www.pathosacoustics.com. In keeping with the amp’s looks, it seems Pathos prefers to place the most user-friendly information of the amp’s technical aspects in plain sight of the user. It requires a bit more looking to delve into the details.
In appearance, the Classic One is longer and narrower than most American amps. This may cause an issue if your cabinetry or shelving is narrower to accommodate the 17” standard. Fine, change it. Yup, this is the kind of component that makes it worth changing out furniture! I have never let my shelving dictate what component goes on it. While one’s spouse may dictate what furniture goes into the room, this amp is a perfect argument for buying new furniture!
The line level-only inputs include TAPE IN/OUT, TUNER, CD, AUX along with one balanced input. The power plug is detachable; having tried no less than six different power cords, I have settled on the Xindak FP Gold, which seems to mate marvelously with the amp.
The included remote is fashionable, its shell being made of the same wood as the center accent name plate on the amp. Three colors are available – black, Walnut and Rosewood (Note! In the MkIII version only Paduk - Rosewood color - is available). The four vertically oriented buttons control (from top to bottom) VOLUME UP/DOWN, MUTE, and SELECT. To switch sources, one pushes the SELECT button and toggles via the VOLUME UP/DOWN buttons. Functionality is simple and clean, pleasing like the amp itself.
There is a renaissance recently for the integrated amp. For a long while, it seemed that integrateds were for Europeans. Americans have a love affair with big, juicy power amps. Separates were the thing. And while it may be true that one can wring out the last bit of performance in separate pre/amp, units like the Classic One begin to challenge that assumption, especially when bridged.
Which would yield higher performance, separates – a preamp tethered to a power amp - or an exceptionally well designed integrated which eliminates a separate chassis and an interconnect? The use of twin integrateds in mono configuration has made my two channel rig as simple as it gets as far as signal path is concerned. Using only one of the amps IS as simple as it gets. The addition of a second amp hardly complicates things, and the benefit over stereo mode is undeniable.
The Classic One MkII is a revision of the original, which met with mixed reviews. The casual listener enjoyed it, but professionals were unimpressed with its dynamics. Gianni Borinato, the engineer who designed the Classic One was listening, and upon its release, the MkII met with rave reviews.
I found the One in stereo mode to be rich and layered in its presentation. I have always been a “detail” freak, wanting the utmost in resolution, but as I have gotten older (and hopefully wiser) in this hobby, I appreciate increasingly products which deliver such detail with subtle nuance - with grace. That’s what struck me about the Classic One MkII; it wasn’t in my face shoving the song at me, but was simply content to sing beautifully and let me approach the subtleties of the music.
Being a tubed integrated, the sound is definitely more “warm” and would be much to the liking of someone who does not want their ears bothered by shrill treble. I used to own Magnepan 1.6’s, and while they have undeniably impressive soundstage and coherency, their treble was always an issue – which is one reason why owners often switch to tube pre/amps to tame the treble. I found that a tube pre was not enough. I wanted even more gentleness in the top-end, without sacrificing clarity or detail, of course! I sometimes wish I had those 1.6’s back again to listen to them now with the Pathos amps! Maybe the treble would be acceptable.
I found that a single One was competent in driving the sizable Chapman T-77’s. Had this never been produced as an amp that was switchable in a moment from stereo to mono, I likely never would have wanted for more. But, because it can be converted to mono merely by flicking the switch on the underside of the amp, well…who can resist? So began my quest for the bridged mode experience.
I am also aware of the conclusion of some that the bass produced by the One was serviceable but not exceptional. Everyone, it seemed, lauded the mids and highs, but the bass was just ok. I also found the bass serviceable but not compelling, that is, until I heard what the bridged units do! Indeed, the bridged One’s are quite a bit better than the single One being used in stereo.
Over the course of my quest to move from one unit to two, I have become an acquaintance of Gianni, who developed Pathos’ Inpol technology employed on their higher end amps. He is quite proud of the One and its virtues. I knew of no one who had ever tried the amp in bridged mode, and the sound quality I was getting from the One in stereo mode was like a siren song luring me to the edge of the unknown.
Gianni was cautious, suggesting that I may enjoy bridging the amp, but would not commit to assenting that the sound would be revolutionized. Well, it was!
The increase in power was instantly noticeable, not subtle at all. The amp in stereo mode supplies 70Wpc into 8ohms. But in mono mode, this jumps to 170Wpc, and into 4 ohms, according to Gianni, reaches approximately 270Wpc!
This is astounding power for the price, and one would pay dearly to obtain this kind of power in quality separates. Gianni made clear to me that the unit was not intended for driving 4-ohm speakers in bridged mode. The unit would handle 8 ohm speakers easily, but was not officially rated for 4 ohms. The concern was to not overwork the transformer. He warned me that pushing the amps too hard could result in damage.
“The Classic One in bridged mode utilizes only the right channel, so that the class-A tube preamp stage is paired with a high current A/AB amp stage.”
The Classic One in bridged mode utilizes only the right channel, so that the class-A tube preamp stage is paired with a high current A/AB amp stage. Thus, only one set of tubes is actually operative in the signal path. I discussed with Gianni in removing the left tube to keep it from unnecessary use. He admitted that he was unsure if it would be wise to do so. We decided to keep the left channel tube in place. Truly, the power and grace of this little number in mono is staggering! I have had tubed pre/amp combinations as well as tube pre/SS amp combos approaching the $10k mark that have not dislodged the Pathi from their favored position in my rig.
I have never been one to attempt “realistic levels” of concerts in my room, so I was not too concerned about over-driving them. From several months of use of these amps, I can say with certainty that the conservative listener, who uses volume judiciously, will never need to worry about using 4-ohm speakers. In bridged mode, such speakers are child’s play to these amps. They have power galore. I rarely need to take the level, which is indicated by red LED’s tastefully residing next to the gold volume and selector knobs on the unit, past 45% of the units’ capacity. Only on some older, very poorly recorded discs, have I used the units at the 60-70 setting out of 100. Even then, there is not the slightest hint of stress. Nor is there the slightest buildup of heat. The Classic One produces negligible heat in my experience. I wouldn’t put it in an entirely closed cabinet, but would have no hesitations putting in on a lower shelf of a rack.
In fact, like the Siren call of the bridged mode, the amps beg you to turn them up! I find myself wanting to listen louder because the relaxed nature of the presentation. I know my ears will not be assaulted, so I take the volume higher…
“I played guitar ages ago, and remember the feel and sound of the “roundness” of the string as it’s plucked. In bridged mode, that roundness comes through convincingly.”
The effect of bridging the amp moves the soundstage forward and outward. Rather than the singer or instrumentalist seeming to be ten feet away, they seem five, like the distance has been halved. This is especially noticeable on solo instrumentals like the unusual The Silent Life by Jonas Hellborg. His acoustic bass guitar takes on immediacy as one can hear not just strings plucked, but the “roundness” of the strings and the sound as it bounces off the guitar’s soundboard. I played guitar ages ago, and remember the feel and sound of the “roundness” of the string as it’s plucked. In bridged mode, that roundness comes through convincingly.
The bass is powerful, tight, but not digital sounding. I had been using a digital amp and tube preamp prior to the Classic One. One of my fears was that I would lose detail in the bass by moving to a tube hybrid amp. My fears were completely unfounded. I discovered that I preferred the Classic One’s bass.
“On lesser amps, the sound of the air could be considered mechanical, but the Classic One reveals the sound is biological. With good amplification, even breath has a discernable tone.”
Regarding some of my listening sessions, Howard Jones sometimes sings, sometimes softly shrieks. I like listening to the shrieks, when his voice falters and the breath takes over as the note dies. It’s not that I like Howard Jones’ voice that much, it’s that I can hear what the components are doing! From the disc In the Running, on “City Song” the bridged One’s put his voice five feet away, with his head turned slightly to one side, slightly more emphasis on one side of the Mic…you can hear his lungs empty out. On lesser amps, the sound of the air could be considered mechanical, but the Classic One reveals the sound is biological. With good amplification, even breath has a discernable tone.
The word Pathos comes from the Greek language and means “deep emotion.” The supplied Sovtek 6922 tubes have a lovely sound. Gianni indicated that Pathos tried several different tubes, but concluded the Sovteks yielded the best sound-to-value ratio. I tried a pair of Electro-Harmonix 6922’s and found them to be slightly more detailed, but also more clinical. I preferred the stock Sovteks and to date have stuck with them.
Bridging the amps also refines the treble; the decay of cymbals is much more discernable than in stereo operation. The room/setting of the recording is far more palpable. The imaging is stunning. Regarding the phantom image, I am aware that the vocals are not coming from my HT center channel, but it sounds like they are. The Pathos amps are so open, so voluminous sounding that nearly everyone who listens, including seasoned audiophiles, ask if the surround system is on. It never is, but everyone wonders.
How did the remote work on two amps simultaneously? Marvelously! My concern was that I would forever be adjusting one or the other amp. I could see a nightmare develop where if I selected a source, or changed the level, one amp would respond and the other not. But this never developed, partly I believe due to the positioning of the amps. They reside about 1 foot apart, centered on the component shelving – and why not? They are gorgeous and should be the focal point of the system! But this also makes it very easy, even for the dual emitting remote, to capture both units simultaneously. Even when using the remote slightly off-center the amps respond in lockstep. Only when the remote is on extreme angles does one amp lag, and this is usually only one digit. A quick flick of the volume control on just the right angle to affect only one unit restores perfect balance. I couldn’t be happier at the coordinated way the two amps work together. Almost invariably the units operate as if there is a physical link between them.
Pathos has just recently come out with the MkIII, which improves upon the MkII by a transformer upgrade and binding posts encased in plastic to increase protection of the amp.
What makes me laugh with glee about the bridged Classic One’s is that these are the entry level amps from Pathos! These were listed at $2,295 but can be found for less new, IF you can still find them, because of the arrival of the MkIII. I consider the fully balanced, powerful performance of two of them to be a bargain at the price point. Pathos is out to prove the point that stunning components can be made for the masses. They’re doing a good job of it!
CLASSIC ONE MkIII in Bridged Mode
Now let’s get to the fun part of the review, since we’ll focus on the MKIII version which is more engaging in every respect!
The physical and electronic differences are such that it can be tricky to determine whether one is dealing with a MkII or MkIII. I recently sold my MKII units, and the buyer called, asking in a worried voice, “These are the MKII version, aren’t they?” The appearance is so identical between the original model and the MKII, and the manual not upgraded to pronounce the new version, that he thought he might have paid for the updated version but received the original! I assured him that he had the correct units; the most distinguishing feature of the MKII’s I found, for reference, is the slot cut in the bottom of the chassis allowing easy access to the Stereo/Mono switch.
The physical changes are listed in the specifications above. As a user, the following changes are operationally significant:
1. The plastic coated binding posts and circuitry to prevent shorting is crucial. I always had a fear in the back of my mind that one loose cable could spell disaster with the MKII; now I am at ease and do not fear for the life of the amps.
I nearly had a heart attack when I first went to hook up the spades of the MIT cables I was using. The MIT’s with their “I-Conn” system have removable terminations. As a necessity, this system uses a “bolt”, which protrudes from the cable, and the termination screws onto it. The end of the bolt protrudes more than a smidgen from the front vertical face of the spades. Meanwhile, the new posts on the MkIII have a funky protrusion on their back side almost exactly where the bolt on the MIT spades hit! Well, not exactly, but close! The posts of the MIT spades just fit into the gap made by the hollow under-portion of the binding posts on the Pathi. I would have been seriously P.O.’d if they were incompatible, but it went. They shouldn’t scare people like that!
2. The improved volume control which can accept up to +/- 12V audio signal can in some cases be a life saver. At about the same time I experimented with the “Pathi” (plural for Pathos; credit for the term goes to Gary, a dual Classic One user in Hong Kong), two other audiophiles triangulated with me; one lives in Hong Kong, the other in Australia. We’ve got the Pathi world covered (thinly, but covered nevertheless)!
My Australian correspondent, Paul, has had a horrible time with the bridged units. He complained initially of weak sound, thin sound, lack of dynamics, etc. (I thought it was just him! Sorry, Paul! J). It wasn’t just him, but it was component incompatibility in the context of his Ayre CX-7 cdp. The Ayre has a 4.5V output, and the MKII amp accepted only up to 2V input. Ooops! Mismatch! No wonder Paul had horrible sound (He had said the amps were so weak that at 50% of available power he could hear his breathing better than the audio system! ) as the amps were being sent a signal outside of their parameters, resulting in input saturation.
This is the only technical foible I have learned regarding the Classic One MKII in bridged mode. Likely, 999 of 1000 users would never encounter this issue, but it’s good to know so that you can check for potential mismatches between sources and the Pathi. Upon learning this, I immediately had to consult my Rega Saturn manual to gain reassurance; it listed 2V max output. I knew from what Paul had described that my player was well within parameters acceptable to the Pathi, for my unit sounded nothing like he described, but for the obsessive audiophile it’s always good to know the numbers.
In stereo mode, the unit seems unaffected. Paul discussed with me how much he preferred the single unit in stereo mode. That convinced me he really never has heard the Pathi in their true monoblock glory. Gianni has been quick to address this weakness, and the MKIII can accept up to 5V input. Those acquiring MkII units in the secondary market for the express purpose of operating them in mono bock mode should touch base with their source manuals to make sure the output falls within acceptable parameters.
3. Electro-Harmonix 6922 Tubes are now standard in the MkIII. The MkII used Sovtek’s, and with that particular unit I preferred them to the set of Electro Harmonix that I received from Musical Surroundings, Pathos’ U.S. distributor. I anticipated receiving replacement Sovteks, but it had turned out Pathos no longer used them. There had been reliability issues, and the Sovteks were no longer being made.
I can confirm the longevity issue from my own experience. I wasn’t sure if it was due to operating the units in bridged mode, as Gianni told me that it had no effect on tube longevity; but I went through three pairs of tubes in just over twelve months, although this was not that big of a deal, at around $8@ for the Sovteks. The tubes would not die, but would drop in output and dynamics about 15%, enough that when it happened I could clearly hear the mismatch between Left and Right channels. Since my units were in mono mode, I kept rotating a good tube into the proper socket and was able to keep going. Finally, the third tube went and I had to obtain a new matched pair.
The replacement Electro-Harmonix 6922’s were a bit more stiff and cleaner sounding. Conversely, the MkIII carries the Electro-Harmonix brand installed from the Pathos factory, and with the tweaking that has been done to the unit I unequivocally state that I prefer the EH tubes in the MkIII to the Sovteks in the MKII. While not a perfect comparison, it does show that Gianni is matching his tubes to amps exceedingly well. I anticipate that the EH tubes will yield longer use; Pathos switched to the EH’s as tube life was an issue with the Sovtek 6922’s. I vouch for the change, as the MkIII is bolder and cleaner sounding than its precursor, yet retaining the sweet sound for which Pathos is known.
4. Curiously, the biding posts utilized in mono mode seem to have been reversed between the MkII version and the MkIII. This is a perfect example of the necessity of reading manuals even if one thinks they are perfectly acquainted with a product. Had I not studied the connections information of the MkIII, I would likely have put the speakers out of phase. This is not lethal to the MkIII’s, but it would mean diminished performance. In fact, I purposely wired the amps the opposite of the manual to determine if possibly a clerical or printing error had slipped into the manual. No, in fact the amps did sound better with the cabling as indicated. But, the sound even out of phase was good enough that most people would never guess it was mis-wired. That’s a mighty odd compliment for an amp!
5. The new op-amp feeding the upgraded transformer has resulted in a much more lux power scheme. Upgrading from the MkII’s to the MkIII’s nearly doubled my usable power. The wattage has not been upped, but rather I suspect the current has been boosted nicely. Experientially, I now use half the level I did previously with efficient speakers and approximately two thirds as much level on less-efficient speakers. Whereas at times I used to float in the 60-70 range on the front digital readout of the amps, now with the MkIII’s I have not gone beyond 37-45 in the loud listening sessions. Truly, I am barely beginning to tap the reserves of the MkIII’s. An impressive demonstration of the newly improved power is the fact that I often had to push closer to 70 on the readout to drive the Eminent Technology LFT-8B’s. Now, I can settle between 45-50 and still feel plenty of palpability, yea, the same impact experientially as I obtained with the MkII’s.
The entire experience the MkIII’s create is cleaner and more intricate than the already good previous version. Just one example; India Aire sings a song entitled “This Too Shall Pass,” with a chorus as follows:
…but
then I hear a whisper that this too shall pass
As she sings this, a small chorus of women’s voices ever so gently whisper the words as she sings them. Using the MkII Pathi, I was only able to detect the echo effect and not the distinct whispering. It took the upgraded MkIII to reveal this ever-so-subtle aspect of the song. The additional clarity takes one to the heart of the piece, as the “angels” are whispering in India’s (and our) ears! That revelatory moment came when the Legacy Focus HD’s, speakers of prodigious expression, were paired with a version of the Classic One that was refined enough to extract the most ethereal elements in the music.
The Focus HD’s, capable of astounding power and finesse for a speaker well under $10k, have reinforced my admiration of the Pathi. It seems there is no end to the upside on the performance of these amps. That, of course, is a foolish statement, knowing that all electronics have their boundaries. So far, however, the boundaries keep getting pushed outward for the Pathi to an extent that it may be a while before I run into one of them.
Other reviews by Doug Schroeder
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Rather
than being housed inside a conservative shell, the ‘guts’ of the amp
sit proudly on display – the transformer, caps, tubes – in all their
glory. It is glorious because the interplay of color makes
the amp very visually appealing. The transformer stainless steel
cover, as well as the casing which houses the other electronics,
contrasts with the black acrylic top plate. Standing prominently in
front of the transformer are the twin massive red caps. The hint of
gold plating on the front knobs (level and selector controls) is
caught again at the back in the vertically oriented binding posts
which straddle the transformer. Just in front of the caps sit the
twin Sovtek 6922 tubes in their attractive chromium cylindrical
cages. Tube replacement is made easy by the fact that one can nudge
the tubes out or in while leaving the cage intact. 
