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Power amplifier


Ayon Audio

Manufacturer: Ayon Audio
Price (in Poland): 77 900 zł (pair)

Hart 18 | A-8101 Gratkorn | Austria
tel.: +43 3124 24954 | fax: +43 3124 24955


Country of origin: Austria

anufacturers of different products have, in general, two main choices – they can adjust to the trends that drive the market at particular moment, or they can try to create new ones, or at least shape the existing ones to their needs. Take any market you want and you will find nice examples. How about mobile phones (nobody calls them that since these are now small computers not just phones) – new trends are made, for example, by telling customers that they can't live any longer without fingerprint identity sensor, so the smartphone they bought less than a year ago is obsolete and they simply must buy the new one, paying more, obviously.

That's just an example – I'm not about to start a war with „i” fans, after all the same company introduced lot of innovative thinking couple of years ago which was a perfect example of how trends, customers needs might be, not even shaped, but invented. What about audio industry? New trends, or maybe rather new branches of the industry are sometimes born too. Few years ago a PC Audio was born – using music files instead of physical medium of any sort, which is already most popular way of playing music among non-audiophiles, and sooner or later will become as popular also among us. On the other hand there is a lot of fuss on the market about DSD files that are supposed to be superior in terms of sound quality but since their availability is even smaller than of 24/192 PCM files it seems absolutely unreasonable to spend lots of money for devices that can play such files. But marketing is a powerful tool and if you ask 10 audiophiles who plan to buy a new DAC whether or not it has to offer DSD files playback probably 9 of them will confirm. So most of D/A converter manufacturers whether they like it or not included DSD playback as a most desired feature in their new models. Luckily for us it might be still more reasonable than fingerprint identity sensor for smartphones... Somewhere between these two examples lays a powerful, like at least few hundred watts powerful, amplification that a „true” high end system has to feature. Doesn't really matter what speakers one has but a huge headroom is a must, just in case.

Of course there are also SET lovers, me included, and companies specializing in satisfying our needs. Just few watts and high-efficiency speakers can make a man very, very happy. So demand is diversified and manufacturers use different means to satisfy the customers needs although in reality there seems to be more of those attractive to hundreds of watts, than SET lovers. So it is safe to say that most audiophiles expect powerful amplifiers, but, despite common believe, transistors are not the only answer. Some designers use tubes too. By definition a single tube can deliver only a limited power, that's why push-pull configuration was invented, and multi-tube amps able to deliver, say, 100W per channel. That still wasn't enough for some. So companies making tubes decided to create more powerful tubes – the biggest ones are still (I think) made by KR Audio (unless some Chinese company made already bigger ones?), but the most powerful ones are specialty of Tungsol, offering a KT tube family, that are usually used in pairs or even quarters in push-pull configuration and total power per channel might be quite impressive. Some time ago KT88 was THE tube for such configurations, but later KT90 was build, and then KT120, each of them offering more power. For some time it seemed that KT120 was a top achievement. Obviously it wasn't as recently Tungsol presented a new top model called KT150, needless to say – capable of delivering even more power. Jadis I-50 was the first amplifier build around KT150 I had a chance to audition. To describe this amp with just one word I would use a: TNT, or dynamite, or explosive, or anything else that could be associated with amazing dynamics, blast of energy and so on. It was as much of a shock for me as it probably was or will be for most Jadis fans.

Despite the fact that many Jadis amp are build around KT88, KT90 and KT120 they all have some common sound signature – their sound is smooth, relaxed, beautiful. Not that it lacks dynamics, French amps offer mighty, punchy bass, but still nobody would describe them as: pure dynamite. And that's what KT150 did with Jadis integrated amp so I couldn't help but wonder what would several of these tube do with monoblocks build by Gerhard Hirt, the guy who's 30W Crossfire SET left me with my jaw on the floor when I first auditioned it couple of years back. Let's get back to the beginning of this text. Gerhard is one of these guys who are able to satisfy needs of wide variety of customers. He did give up a 300B triode some years ago in favor of more powerful versions of this legendary tube delivering „only”, respectively, 20 (52B) and 30 (62B) watts per channel. So no hundreds of watts of power, so they require speakers with at least average sensitivity, but if you give them a chance they will overwhelm you not only with triode magic, but also with impressive dynamics that owners of some even more powerful solid-state amp may only dream about. On the other hand Gerhard offers also a 75W PSE amplifiers, which is already an impressive figure, but also real beasts like Orthos XS, that, still using tubes (although from KT family) can deliver hundreds of watts of power. Those who visited Ayon Audio distributor's room during last AudioShow had a chance to listen to the mighty Orthos XS monoblocks driving Dynaudio speakers, but as we all know presentations during shows never reveal true potential of presented equipment. Anyway, during the show I talked briefly to Gerhard and asked him about his (not so long) experience with KT150 tube and he confirmed that it was a very interesting product, with huge potential, that allowed his monoblocks to sound even better than with KT88 or KT120 (not to mention higher output power).

What I heard there definitely caught my attention (but I should say that I listened on Sunday before first „official” presentation so in slightly different conditions than most people), but while looking at those beast I didn't even think about requesting them for a review. They weighted 50kg each without packaging, and since were delivered in wooden cases it was more like 70 kg per piece to be carried up three floors to my apartment. I looked at Orthos XS and my back told me: don't you even dare to think about it!!! Well, I didn't. But you know what they say – fate is a b... I didn't ask for them to avoid carrying them so Wojtek did ask, and not for himself but for me – thanks boss! I didn't have much choice but to state clearly that they had to be delivered right to my listening room, unpacked and placed on stands without any participation from my side. Nice guys working for Polish distributor not only brought these two beasts but added also an Ayon Polaris II – not the smallest, two-casing, high-end tube preamplifier. Orthos XS depth is at around 6ocm so there was no way to put them on my regular rack. They had to be placed on the floor, on granite stands I usually put under speakers and they still barely fit there. One can get scared seeing the number of tubes to be put in each monoblock - 14 (!!) pieces per one. You get 10 power tubes (in this case KT150, although this amp can be fitted also with KT88 or KT120) and four small signal tubes. And remember that there are two monos so what you get is a hell lot of tubes. You want more reasons to get scared? Have a look at the specification – these are “only” tube amplifiers but still while using KT88 they are capable of delivering 250W per channel (in pentode mode) and 150W (in triode mode). Trade KT88 for KT120 and the numbers grow to, respectively, 300 and 180W per channel! Trade again to KT150 and I guess even Gerhard got scared as Ayon's webpage doesn't even give you the numbers, but if you check the parameters for KT150 alone you'll see that each of them is capable of delivering 35-40W, which leads to conclusion that we might be talking about 350-400W (in pentode and probably at least 200W in triode mode)! Even the numbers given with KT120 are already impressive and rarely seen among tube amplifiers, but these with KT150 (assuming my guess is right) should impress even solid-state guys.

I got scared too – hundreds of watts per channel and all speakers I had at my disposal at the time were high-efficiency ones – my own Bastianis Matterhorn, Ardento Alter1, Amphion Argon 7L and Zingali Home Monitor 2.8. Well I started with switching Orthos XS to triode mode, then I used small switched placed at the back of amplifiers that lowered gain by 6 dB. Then, for a moment, I considered hooking these beasts to my bookshelfs instead of to any speakers – I was pretty sure it would made my books sing, but I realized that books would be most likely blown away from shelves and I would have to spend couple of hours putting them back... All right, sorry for improper jokes – I was simple getting nervous. I think probably no other amplifier I had ever tested before got me that worried even before I actually started to listen to it. And the reason in this case was what I remembered from my listening session with above mentioned Jadis I-50 that sported only two KT150 per channel. It seriously had tried to tear down the walls of my almost 100 years old building that managed to survive a Second World War once, and more than 40 years of communism – I had said “TNT” before, remember? And this time I was about to turn on 10 such tubes per channel – so it wasn't just about the building any more, more likely about the whole quarter... What the hell, I said to myself, let's do it. Just in case I send my family for a long walk far away from home, I turned Orthos XS on and...

Recordings used during test (a selection):

  • Isao Suzuki, Blow up, Three Blind Mice B000682FAE, CD/FLAC.
  • Keith Jarret, The Koeln Concert, ECM 1064/65 ST, LP.
  • Arne Domnerus, Antiphone blues, Proprius PRCD 7744, CD/FLAC.
  • Marcus Miller, A night in Monte Carlo, Concord Records B004DURSBC, CD/FLAC.
  • AC/DC, Live, EPIC E2 90553, LP.
  • Kate Bush, The sensual world, Audio Fidelity AFZLP 082, 180 g LP.
  • Joseph Haydn, Les sept dernieres paroles de notre Rédempteur sur la Croix, Le Concert des Nations, Jordi Savall, Astree B00004R7PQ, CD/FLAC.
  • Dead Can Dance, Spiritchaser, 4AD/Mobile Fidelity MOFI 2-002, 180 g LP.
  • Krzysztof Herdzin Trio, Almost after, Jazz Forum Records 020, CD/FLAC.
  • Miles Davis, Tutu: Original Recording Remastered 2011, “Deluxe Edition”, Warner 081227976873, CD/FLAC.
  • Rodrigo y Gabriela, 11:11, EMI Music Poland 5651702, CD/FLAC.
  • Renaud Garcia-Fons, Oriental bass, Enja B000005CD8, CD/FLAC.
  • Hans Zimmer, The Dark Knight Rises, WaterTower Music B008645YEE, CD/FLAC.
  • Hans Zimmer, Inception, WaterTower Music B003ODL004, CD/FLAC.
  • Whitesnake, Starkers in Tokyo, EMI Music Distribution B00000IGV9, CD/FLAC.
  • Nathan Riki Thomson, Under Ubi's Tree, Naim naimcd 114, CD/FLAC.
Japanese editions of CDs and SACDs are available from

… very soon after that the Polish Army Chief Command situated maybe 200m from my home raised DEFCON level from 5 to 4 (or whatever they call it in our army), which was their a reaction to a sudden and unexplained drop of voltage in the whole local power grid. For the first two days I had to play at really low levels to avoid being detected by numerous patrols sent to look for saboteurs. Luckily I managed to stay undetected and couple of days later they stopped looking... :) I didn't even try to check how much power Orthos XS used but considering how quickly and how hot it got in my room I would say – quite a lot. In other words – nihil novi sub sole, as far as Ayon amplifiers go. Normally I wouldn't even have mentioned that but I meet so many people again and again who are so surprised that tube amplifiers, and class A solid-states generate so much heat, and are so „Eco-unfriendly” that I have to mention that. Yes, tubes and class A (tube and solid-state) do involve a lot of heat. Yes, using them will increase your power bills. Yes, that's exactly what makes them sound so damn good! During my tests Orthos XS didn't have to use their huge power headroom since I hooked them up only which high-efficiency speakers. But considering how much power one gets at one's disposal - few hundred watts in class A - there are probably very few loudspeakers on the market that could cause any trouble to these beasts at all. The separate 4Ω (I mean apart from standard 8Ω) speaker posts will help too. Maybe, just maybe, some speakers with their impedance diving regularly as deep as 1-2Ω could cause some trouble but if you have such speakers you'd have to check it yourself. Anyway the Austrian Ayon Audio now offers an amplifier also for those who believe that high-end sound might only be delivered by a few hundreds of watts, or simply have current hungry speakers. I mentioned already that nice guys from Eter Audio were kind enough to bring also a Polaris II preamplifier, that was surely a better match for Orthos XS than my (fantastic, but from a bit different league) LS100, and my main digital source for this test was the recently reviewed, amazing Ardento PerfectDAC, that I managed to keep for some time even after the test.
Every amplifier designed by Gerhard Hirt so far impressed me with amazing dynamics regardless if they offered 20 or 75W of power. I listened to most of the 52B/62B family from Merkury, Crossfire to mighty Vulcan and loved them all. Not only did they offer a lot of 300B-like triode magic but also so much energy, such a vivid, agile sound. So now I couldn't help but wonder if the new amp sporting 10 most energetic tubes I know per channel – the KT150 - would impress me even more in these aspects.

It was not about 20, 30, or 75W per channel in SE (or PSE) from more powerful cousin of magical 300B, but hundreds of watts in push-pull configuration of a more powerful cousin of the (not so magical if you ask me) KT88. So different tubes, different configuration, different „wattage” league – even the same designer couldn't guaranty similar results.

My first choice for listening session with Orthos XS were Ardento Alter1 speakers and… there was no this: „Wow! What a dynamite” effect, that I'd experienced while listening first to Jadis I-50. Why not? Well, first of all what I'd heard from Jadis was totally unexpected, very different from anything any other amp of this brand offered me before. Orthos XS on the other hand sounded as I could expect from any Ayon product – they sounded great, dynamic, energetic, well „ayon -ish” so to speak, so there was no such a huge contrast between what I expected and what I actually heard. Again, to be perfectly clear – it was a powerful, punchy, vivid sound but what attracted my attention (while listening in triode mode) at first was... midrange – smooth, rich, colorful, with lots of air, openness – in other words exactly what one could expect from a very good SET, a lot like what I heard from Vulcan amp (based on 62B triodes). But I asked myself again – why was it the midrange that attracted my attention at first? Well, most likely because Orthos XS offered quite a linear presentation throughout the whole range. There was no emphasis on any range, any particular frequency, but it was midrange that our ears were most sensitive to, that contained most audible information, so even the impressive, mighty bass wasn't able to dominate it. It was also possible that I actually expected on subconscious level to be overwhelmed with bass, with raw power of Ayon amplifiers so when it didn't come my attention shifted to other, most obvious part of the performance. Let me repeat myself again – Orthos XS did not lack anything in bass range – not only was it punchy, powerful, but also colorful, very nicely defined, very, very deep and beautifully combined with the rest of the range. For example Isao Suzuki's bass on Aquamarine from Blow up properly shook the walls of my room and every little bone in my body, but even though it allowed me to hear clearly every detail performed by other instruments, it allowed each of them shine on its own. Same went for Marcus Miller's electric bass guitar, or some heavy electronic bass on Dead Can Dance recording – lots of very well defined power, great differentiation, impressive pace&rhythm, but they never dominated recordings, at least no more than it was intended by sound engineers. It was the 15'' Ardento's Atler 1 woofer that benefited from Orthos XS most. This paper cone performance was simply spectacular – it went down as low as it needed to, there were no shortcuts, not emphasis on upper or mid-bass, no tricks were needed as it delivered everything it was required to in a powerful, orderly fashion. It provided not only a sensation of physical power that I could not only hear but also feel, but a solid base for the rest of the range that clearly benefited from it. This way I was offered a full-range, most impressive performance.

Powerful, dynamic performance is not the only clear advantage of Ayon Orthos XS. It still sounded like a very good tube amp should have. Amazing imaging, 3D rendering of sound sources, wonderful timbre, natural sweetness – all that was there. These Ayon amplifiers combined power, dynamics with smoothness, richness and colorfulness of the sound in a most impressive way. I was truly thrilled listening to many (recorded) live performances. Using phonostage implemented in Polaris preamplifier I played a wonderful Jarret's Koeln Concert and I sat there holding my breath (unlike quite a large number of people who actually were there instead of in some hospital because of their obvious pneumonia) waiting for what was to happen next (yes, of course I had listened to this record dozens if not hundreds of times before, so what?). It wasn't just about how powerful, mighty even the piano sounded, it was about the beautiful sustain and decay, about how many different sounds was this amazing pianist able to force into the space, how realistic were the sounds made by Jarret himself. I was totally... immersed into music, into this fantastic spectacle – I mean I was so involved that I had to watch myself not to give scary looks to all these guys coughing around me and spoiling this extraordinary experience. Having that much power and such a great speakers to go with it I had to play Antiphone blues too, just to remind myself how convincing mighty organs sound even when you play them at home using proper system. And again – all this power, while totally impressive, allowed me to equally enjoy amazingly pure, detailed, crisp sounding saxophone. Plus I could „see” the huge space where this performance was recorded in. This presentation is not about overwhelming listener with immense power of the amplifier. This power is just a means of delivering performance in as realistic fashion as possible, with almost live-like dynamics. Obviously it's not a true live-like experience – no audio system can deliver one. So what we get is some estimation of live music, but I have to say that a good, involving and charming one. Large output power allows amplifiers to control speakers perfectly, it allows them to define every little sound with precision, to provide a fast attack, slow decay, and, if needed, a nice, long sustain. Orthos XS was also one of quite few amplifiers that encouraged me to study recordings, not just music but recordings. I don't usually do that – I prefer to listen to the „bigger picture”, to the music as a whole, and not to analyze every little detail. Those details are necessary of course, as they together create this bigger picture, but I'm not a fan of highly analytical systems that put an emphasis on presentation of those details rather than on music per se. Ayon amps gave me a chance to listen to very rich, detailed, precisely constructed musical spectacle but this particular way of presentation made me want to dive into discovering, tracking down many tiny, little details that I'd usually omitted. Drummer's stick hitting drum or cymbal, how these reacted (yes, here the action equals reaction rule also applied), reverbs suspended in the air almost for ever, plucking a string, watching it resonate, and so on, and so on – all these were elements of a bigger whole but they were so easy to spot and follow that even I was eager to do just that. To deliver all that Orthos XS had to be resolving, and offer detailed and highly selective sound and it did – these were clear advantages of those Austrian beasts. Equally important was another advantage already mentioned before – Ayon was very linear throughout the whole range. All impressive parts of the range came together smoothly – mighty, punchy bass, rich, colorful midrange and open, vibrant treble. There is no sign of any brightness, harshness, nor graininess in the treble – there are, on the other hand, very clean, rich and smooth but also sparking high tones. That's why I enjoyed sound of cymbals so much for example on one of my favorite Krzysztof Herdzin Trio's recordings – so vivid, so sparking, so nicely differentiated, or cymbals on Miles Davis' Tutu shimmering in the background. You get also an impression of a very open sound, with lots of air surrounding instruments, filling space between them, making them all breathe. There is some sort of... crispness in this sound, something that makes you want to listen more and more, as you feel this direct, personal contact with music, musician, vocalist, that again brings you quite close to live experience. As a fan of 300B SET magic I'd say that vocals delivered by Orthos XS are not that „magical” as Western Electric 300B tube in a proper amp can make them, but hey – no other tube can really do that, can it? And you can't have it all – this amplifier has so many other advantages that nobody will seriously miss this elusive 300B „magic”. There is magic here too, but of a slightly different kind and it still offers tones of emotions, close, almost intimate contact with musicians and vocalists. You want a proof? Just listen to some nice vocal piece in some exotic language you can't understand at all – if you still feel true emotions, if you can feel the mood, if start to smile, get sad, touched, moved and so on (still not understanding a single word) than you know exactly what I'm talking about. Emotions are an universal language. It is easier to understand when you can actually see the other person but if you can't because you're just listening to the recording and you still understand it – that's a job well done by your audio system. Orthos XS convey emotional content of recordings damn well, they do it in what seems to be totally effortless way creating a bond between performing artist and listener – fantastic!

Although none of the speakers I tried with Orthos XS really required it I still tried also a pentode mode – more power, volume down, let's see what happens. Honestly the change of sound, or sound character wasn't to significant regardless of which speakers I used. The pentode mode seemed to offer a sound that was a bit tougher around edges, even more punchy, but with also tad less sweeter midrange and treble. Listening to some recording I thought that maybe the sound was also no so 3D as it was in triode mode. Personally, in general, I preferred a triode mode, but I couldn't deny that when it came to AC/DC concert or a powerful, dark OST from last Batman the pentode mode had its charms. It sounded even more powerful, more energetic, and bit more raw, if you know what I mean, which was exactly what this kind of music needed. But again – that's nothing else but another advantage of this amplifier. Basically a sound character will be the same in both modes but changing one to another will give you even more pleasure while listening to a particular recording. And switching is so easy that you could do it each time you feel like it to adjust sound a bit to your liking, to your mood, or to the music. I love it, don't you?


Orthos XS might be an ultimate amplifier, end of the search for many audiophiles as well as music lovers – that doesn't happen often. Impressive output power on one hand, sophistication and linearity of the sound with just an ounce of tube magic on the other. Such a high output power should put considerations of high-power solid-state fan to rest – power can't be used as an anti-tube argument any more. Now the choice between tube and solid-state amplifier has to be made upon some other features. Tube fans won't be let down either, as the „muscles” don't overwhelm what we love about tube most – timbre, holography of the presentation, naturalness and smoothness of the sound. I don't really see hardcore solid-state freaks complaining – lots of power – check, impressive dynamics – check, clarity of the sound – check, and it also sounds resolving and transparent. Congratulations for Gerhard Hirt are in place – his pursuit of new, better solutions lead to better sound and more versatile designs – he simply did it again!

Orthos XS is a tube mono power amplifier. Let me clear that now – large, heavy ones, huge some might even say! Weight (net) 50kg a piece (they are packed in wooden cases so shipment weight of a pair is probably close to 150kg). The largest dimension is depth that reaches 61cm so before you buy them make sure you have something you might put them on, as most standard audio racks won't accommodate them. I used 60x40cm granite stands that normally are placed under speakers. It's easy to say that these beasts are of Gerhard Hirt design – all his amplifiers look, to some point, the same – solid, black casing with round corners and large silver cups holding transformers inside give it right away. Inside those silver cups there are high-performance, wide-bandwidth output transformers, and low-noise power transformers sealed with an anti-vibration compound material. In front of those silver cups, still on the top cover there are sockets for all tubes. There are two rows on the right and left side each containing 5 power tubes, and the four small tubes sit in the middle. Orthos XS I received for a test included a set of the Tungsol KT150 power tubes, but the same amplifier could use also other tubes from KT family – KT88, or KT120 (different tubes mean different maximum output power). The four tubes in the middle are two 6SJ7 rectifiers, one 12AX7 and one 12AU7. Behind them you will find a simple switch that allows you to chose one of the operating mode – you can chose either triode or pentode mode. There is also a very nice VU meter that comes handy if you want to check a bias current for each individual power tube (a switch on the back panel of the amplifier allows you to chose a particular tube). Orthos XS sport an auto-bias system developed by Gerhard, but it is quite a different system from those used by other manufacturers. If you use this amplifier for at least 45 minutes then when you turn it off it stays on until the auto-bias system measures bias for each power tube. The values for each of them is than remembered and used next time when you turn amp on. In case of failure – meaning a value outside predefined parameters automatic system won't let you turn the amp on, and a small red LED on the back panel will indicate a faulty tube. Orthos XS sports also a soft-start feature that will prolong tubes' lifespan. So when you turn amp on a red Ayon logo on the front on the device blinks for about a minute when circuit is warming up and after that period of time amp is ready for operation. On the back panel there is actually a small display that counts down these 60 seconds after ON button is pressed. Like in all Ayon devices next to power inlet there is a red LED that indicates proper polarity. There are solid, gold plated speaker binding posts separately for 4 and 8Ω loads. Next to them you will find XLR and RCA inputs – only one of them might be active and there is a small toggle switch to chose one of them. There is also another toggle switch nearby that allows you to lower the gain by 6 dB, and another ground switch, useful if you have some ground loop that causes audible buzzing.

Technical specification (according to manufacturer):
Class of operation: triode or pentode mode, class A
Tubes:10 x KT150 per channel
Load impedance: 4 or 8 Ω
Bandwidth:8 Hz - 70 kHz
Output power (pentode) KT88/KT120/KT150 1 x 250/300/? W
Output power (triode) KT88/KT120/KT1501 x 150/180/? W
Frequency response:15 Hz - 40 kHz (+/- 0 dB)
Input impedance @ 1 kHz: 47 kΩ
Input sensitivity (full power): 1,2 V
S/N ratio (at full power): 98 dB
NFB: 0 dB
Inputs: RCA + XLR
Dimensions (WxDxH): 350 x 610 x 250 mm
Weight: 50 kg/unit net