The Effortlessly Nuanced Apex Audio High-Fi Teton OTL Headphone Amplifier

Having just reviewed a few inexpensive headphone amplifiers, I now turn back to a high-end contender: the Apex High Fi Audio Teton. Apex High Fi Audio is essentially the house brand of online headphone and audio retailer Todd The Vinyl Junkie. The Teton is a vacuum tube, "OTL" (output transformerless) headphone amp of considerable size and girth. When I was unpacking it, I immediately had a flashback—the tube compliment is EXACTLY the same as the Wheatfield Audio HA-2, which is a long discontinued amp that I owned for quite a while, and really liked. Well, it is the same designer, Pete Millett, and the heritage is clear, but the TTVJ website also makes it clear this is a highly refined evolution of that venerable design. The Teton is actually the second-from-the-top-of-the-line Apex amp, behind the $10,000 Pinnacle.

This Millett design uses a 6SN7 dual triode as the input tube, a 6AS7/6080/7236/5998 as the output tube (also a dual triode, but a much larger and more powerful one), and a 5U4GB as a rectifier tube. It's a very large amp, in a nice looking black anodized chassis. No one will complain about the price per weight of the amp, but I do think some people who will consider spending $5,000 on a headphone amp may wish for a bit fancier chassis. I'm more interested in the sound than the looks, as long as the thing isn't butt-ugly, and the Teton is far from that. It's also VERY solidly built.


The Teton has three inputs on the rear panel on VERY nice chassis mounted RCA jacks, which are front panel switchable, and it has a preamp-only setting. It certainly could be used as a nice preamp in addition to a headphone amp. There is an IEM setting, which very clearly reduces the gain. I don't own any IEMs, so I didn't use this setting, but when my LCD-3's were plugged in and I switched to the IEM setting, the volume dropped very noticeably, so it's clear what the amp is doing here, and I'm sure IEM owners will be grateful for this feature.


Power output isn't specified, and the TTVJ website doesn't provide much in the way of specs, but does indicate "for 16 ohm and up headphones". The Teton had no problem driving the LCD-3 to levels far beyond which I would normally listen. And every bit as importantly, it did so without noise or hum. I have heard 6AS7-based amps that ALWAYS had some residual hum, and in fact, my Wheatfield HA-2 was among them. Not the case here, so perhaps that is one of the design improvements.

I listened to a wide variety of music on the Teton, which I fed directly from the analog outputs of my Pioneer N-50 Network Music Player/DAC. I played mostly high-resolution (96/24 or higher) digital audio files. I did also connect it briefly to the tape output of my Pioneer SX-1980 receiver so I could listen to it playing vinyl and reel tape. I listened mostly to the Teton with the Audeze LCD-3's.


A Teton is...
Well, the Tetons were an American Indian tribe from the Dakotas. Not sure if that was what inspired the name of not, but there it is. The real power button is on the rear—the front panel switch toggles between standby (tubes off) and full on. Not sure exactly what is powered up in standby mode, but I certainly like having the full off switch as well.

I was immediately VERY impressed with the Teton. I have been reviewing some less expensive amps lately, and while they are actually very nice, and the last one I reviewed was 10% of the price of the Teton, there is no doubt that you DO get something for your money. The Teton provides a level of openness, detail, transparency, and delicacy that sadly, you DO have to pay for. It doesn't come cheap, no matter how nice that would be.

Music played from the Teton flows in a remarkably effortless way. Listening to the new album by Yes, "Heaven & Earth" (which in spite of a number of fairly negative reviews I actually like quite a bit), the lushly layered "To Ascend" was absolutely beautiful. The three part harmony chorus vocals were just gorgeously rendered. Maybe people who didn't like this album listened to low bit rate MP3's of it and were not "getting it". I don't know. But the beauty of the vocals, guitars, and keys of this track, all of which like squarely in the all-important midrange, were a delight. You really can't ask for better midrange performance from a headphone amp than the Teton delivers, and even if you do ask, you aren't going to get it, in my experience.

Having been put in the mood for harmony vocals, I then switched to the new BluRay release of Crosby, Stills, Nash and Young 1974, which is all live material from that year. The audio is 192/24, and it is really impressive for 1974 live sound. The soundstage is very evident, and on Neil Young's powerful "Helpless", the four singers were spread out in a very believable, natural way. Depth of field on the soundstage was excellent, as was lateral image placement. The width was not the very best I have ever heard, but was nonetheless very good.

The treble performance of the Teton was definitely world-class—sweet, delicate, nuanced, clean, and not at all rolled off. This isn't that easy a trick for a tube amp that isn't both well designed and well implemented, but the Teton pulls it off well. There is a wealth of treble detail in Holly Cole's "The Train Song" from "Temptation", and the Teton rendered all of it splendidly. Listening to the Japan SHM-SACD of this release was thoroughly enjoyable via the Apex. The ability to deliver lots of treble detail without any tendency to brightness seems to me to be something of a lost art in audio design these days. But that is just exactly what you get from the Teton—all the treble detail and nuance you could hope for, without ANY brightness or glare. Unquestionably something to delight in.

There was one area of the amp's performance that I wasn't completely smitten with, and that's the bass. I did feel that the bass was slightly underweight. What bass was there was truly excellent - well defined, tight, and punchy, but in comparison to other amps, there was simply less bass weight than I think is completely accurate. It's possible that tube rolling might be able to ameliorate this, but I wouldn't count on it. I used the tubes that were supplied with my loaner unit, which were some very nice vintage US tubes (Tung Sol 2399, Sylvania 6SN7W and 5U4G). I think of the 2399 as being a tube with excellent bass (I own and have used this tube frequently), and ditto the 6SN7W.

On music that doesn't really feature a lot of powerful bass, like the inexplicably underrated Rolling Stones album Black and Blue, the bass balance of the Teton wasn't in and of itself noticeable at all, and the groove that makes up "Hot Stuff" grooved right along as it should. It was only with something like Porcupine Tree's "Russia On Ice" from the musically and sonically phenomenal album "Lightbulb Sun", which contains some VERY deep and powerful bass, that I found myself wanting a bit more weight. One shouldn't ever have LCD-3's on one's head and think, hmmmm, I wish there was a bit more bass. And yet I did sometimes feel that way. The bass was plenty deep, that wasn't the issue. You get the full frequency range. Some people will probably think the bass balance is perfect—it just depends what you are looking for. And again the bass that you get is excellent. I just found myself wishing for a bit more of what was there.

That's Teton, not Tectonic
OK, so it doesn't spark earthquakes with its bass pyrotechnics. Still, this characteristic of the Teton has to be viewed in the context of what the amp delivers as a whole, which is pretty spectacular performance. Most of the time I would describe the performance of the Teton as "breathtaking". "Dancing With The Moonlight Knight" from Genesis's "Selling England By The Pound" was so gorgeously rendered that I got goosebumps that lasted a LONG time. That's not even remotely slouchy. I could very happily live with this Apex amp as my only headphone amp, and I will be sad to see it go. Still, $5,000 is a serious investment, and I believe one needs to consider such investments carefully. Like pretty much every audio device ever made, it's not going to be for everyone. Crazy bass freaks probably should look elsewhere. But if you like to be wowed by the beauty of music, the Teton is definitely worthy of consideration.

I do feel the Teton is deserving of being included in InnerFidelity's "Wall of Fame", with the understanding that not everyone is going to be in the market for a $5,000 headphone amp. For those lucky people who can consider such an investment, I would strongly recommend checking out the Teton.

Editors Note: Dear reader, I'm going to have to apologize. I had this amp for a few weeks and loved it...but didn't have time to review it myself, so I offered it to Skylab for review. Knowing the amp had to get back on the road for Todd's Teton Loaner Program, I asked him to move forward with the review as quickly as possible. For a variety of disparate reasons, Skylab at the time had a reduced number of headphones available and reviewed the amp with an LCD-3. Being an OTL amp, the Teton has a relatively high output impedance (around 50 Ohms depending on the output tube used), and is not an optimal match with Teton, which really prefers high impedance headphones like the Sennheiser HD 800 or AKG K701. It is a testament to how good this amp is that even with the LCD-3, Skylab's impression was, "I did feel that the bass was slightly underweight. What bass was there was truly excellent - well defined, tight, and punchy, but in comparison to other amps, there was simply less bass weight than I think is completely accurate." The problem here is the headphones and not the amp. Unfortunately, we didn't manage to figure out we had a problem with this review until it was finished and the amp on its way home to go back on tour.

As I said, I did spend quite a bit of time with this amp with higher impedance headphone and found it absolutely stellar in every way, including bass response, for an amp of this type. No, this amp will not deliver slam and tooth rattling thump like a world-class solid-state amp, but with high impedance headphones it does it as well as other best-in-class tube amps of this type. Had I had the time I would have reviewed the amp myself and put it up on the "Wall of Fame."

One option was to simply delay the review, but unfortunately that would have meant many, many months before the gear would become available again. Because I felt Skylab did an excellent job of characterizing this amp and it's gorgeous mid-range and treble response, and because I had heard the amp with high-impedance cans and knew I could comment here, I decided it would be best for all concerned to produce the review and attach these comments. Apologies to all.

TTVJ home page and Apex Teton product page.
Head-Fi threads here and here.
TTVJ Teton loaner program thread on Head-Fi.

Todd The Vinyl Junkie
405 2nd Ave East
Three Forks, MT 59752
866 444 3910

MacedonianHero's picture

Great write up Rob! I really enjoyed your review and I hope to hear this amp one day! I've heard the Peak/Volcano and thought it was one heck of an amp. Looks like Todd's got another winner from Pete Millet

TheAudioGuild's picture

Beautiful! Nice to see a high end amp only sporting a TRS jack on the front panel. ;-)

Seth195208's picture

If you know that the Tetons are a mountain range and that Apex names it's amps after them, the Indian tribe comment would be funny.

Limp's picture

Téton also means nipple in conversational french.
The word came from french-canadian hunters who saw the mountain range in question, and thought it resembled a series of female breasts pointing up at the sky.

Todd's picture

I would like to thank both Tyll and Rob for taking the time to listen and review/comment on the Teton. We are very proud of this unit and feel it got a fair shake and review here. Thanks guys and look forward to your continued success in delivering great reviews of products we all want to know about!


bronson's picture

Seriously - $5K?

And their top of the range amp is double? I wonder if you get double the SQ?

And people say beats headphones are expensive - lol

Would have been interesting to see how the solo2 sounded through this uber expensive amp.

To roll those tubes, you've got to be a high roller for sure.

Tyll Hertsens's picture
Welcome to the high-end. I've got to say, a lot of times with this level of gear you pay for casework and shiny knobs. With the Teton you really are getting seriously good bits. If you don't get it, that's fine, just walk away. If you do get it, this is one to audition.
bronson's picture

I thought high-end was the likes of the HFM EF-6 amp, which I own and use for mainly the HE-6, but also use it with the LCD-X.

Granted the Teton is a tube amp, compared to solid state EF-6 - I don't know if tube amps command a premium in general, but I'd love to hear the Teton for sure, but don't think this amp is so easily found outside the USA.

Maybe if I heard the Teton, I'd understand why it commands it's price tag, but maybe I'm better off in the pocket if I don't, as this hobby can get very expensive as I've discovered and chasing that better sound whilst a lot of fun can sometimes get a bit obsessive and be more gear centric rather than enjoying what you already have.

But I enjoy reading your reviews on such exotica for sure, I think my original shock comment at the Tetons price tag is because I've no experience with this level of amp unlike yourself who has experience with amp I use, the EF-6, so understand the difference in quality between the two, whereas I read your review, then see the Tetons price and automatically think - is it really four times better sounding than the EF-6?

I guess I shouldn't query a products price point without understanding this class of amp and of course hearing it in person which ultimately decides it's value to acquire or to pass on.


n_maher's picture
It's not really that expensive for this amp unless you want it to be, which is pretty much the same story for any tube-based audio component. As someone that has owned no fewer than three similar amps (the original HA-2 and two heavily modded DIY versions) there are very good sounding tubes available at reasonable prices. If you want to part with loads of cash you can certainly do so, but it's not required to get great sound. As for the rest of your comment, Pete and Todd are hardly the first nor will they be the last to offer high-end gear at a price that makes some of us blush. But at least in this case the guys behind it are two of the most honest, down-to-earth folks you're likely to find in this arena. Are they making money selling this gear, you betcha, but I'd wager you enjoy getting paid for the work you do as well, eh?
Skylab's picture can find quite enjoyable NOS variants of all three tubes used in this amp for $25 or less per tube. I can easily imagine an all-RCA trio of tubes would yield an even lusher, if somewhat less transparent sound. Lots of affordable possibilities here. Yes there are also some uber-expensive tube options as well but at least that's not mandatory...
dripf's picture

How is it 'high-end' when it uses an inferior single-ended design, Tyll? Is it a 'level of gear' to be outclassed by a $350 headphone amplifier? This thing has no specifications and probably has audible distortion. I can enable a configurable distortion plugin on my computer at no cost if I care to. Casework and shiny knobs are half of what you get when you buy a Violectric over a Lake People, and it doesn't cost $5000.

I don't want to read reviews of this trash. In fact, I don't want to read tripe about 'listening' to amps or dacs.

Vic's picture

I don't want to read about interior design. So I tend to avoid those types of articles when they pop up on websites I otherwise enjoy. I would not demand these sites stop publishing these types simply because I find them obnoxious. Do you see the parallel here at all?

Tyll Hertsens's picture
I don't find single-ended designs inferior. Sure, it's a topology that allows more distortion than a solid-state AB amp, but it's distortion of a nature that is pleasant somehow. Pete is a master at drawing out the yummy goodness of tubes.

Again, if it's not for you, fine. But if you, like me, do appreciate the characteristics of a well designed tube amp, then this baby deserves a good hard listen.

n_maher's picture
He said interior, which I find confusing unless he's referring to the fact that the review actually (thankfully) discussed some aspects of the circuit design. Otherwise color me confused.
n_maher's picture
So what is it about this particular single-ended design that you believe to be inferior? You seem to be leaping to a whole lot of conclusions with little to no basis. Now that's definitely the type of tripe that I have no interest in reading.
dripf's picture

There is no contention that a $110 FiiO model will outperform this one, even by reason of output impedance alone. It can do everything better except loudness.

I understood Tyll's perspective before he reiterated it. My counter-argument is highlighting the illogic of 'because it uses a largely abandoned design, it is naturally fitting for it to command such non-linear value.'

Vic's picture

My earlier comment about interior design was in regards to interior decorating. Like all those home makeover type shows. I have zero interest in that sort of thing but sometime come across it in magazines and websites that I otherwise enjoy. I just skip that stuff rather than talk about how unnecessary I find it. I could just have easily used a different analogy like "baking" or "architecture" and the point would be the same. Sorry for causing confusion.

Dripf I don't see why you are here if you think a Fiio amp is the pinnacle of hifi reproduction. It's like trolling a vintage sports car forum and pointing out how superior a modern car is. What's the point?

minimus's picture

In my experience, whether a component is balanced or not tells you almost nothing about how good it will sound, and consequently whether it is worth its asking price. I have owned balanced headphone amps, preamps, and speaker amps that were trounced by single-ended designs, some more expensive, some less expensive than their balanced counterparts. (For example, I own the Teton and have used it as a preamp in place of my $7,500 fully balanced Zesto Leto. Guess what? The Teton is a better sounding preamp than the Leto.)

Also, I agree wholeheartedly with Tyll's postscript. The Teton is far from bass light with high impedance headphones like the HD800s. When using HD800s, I find it has better bass than my Eddie Current 4-45, the current top-of-the-line offering from Craig Uthus. Anyone who thinks the HD800s are bass-light should listen to a pair of them plugged into the Teton. It is a stellar sounding amp and is not lean in the slightest with the right headphones.

dripf's picture

Do you understand why this model produces greater bass with the HD800? It is not because the amp is superior.

minimus's picture

Don't assume everyone but you is an idiot. The Teton is an OTL design, so its output impedance is high, making it a better match with high impedance than low impedance headphones.

No, the amp is not "superior" because it is an OTL topology. It is "superior", at least in my mind, because I have owned ten other headphone amps in the last decade, including two that cost just as much as the Teton, and it sounds better and has better build quality than any other amp I have owned.

I understand that some people can't afford this amp, a group that may include you. But stop claiming that this amp is not worth its asking price. You haven't heard it, so how would you know? I just stated that as a preamp the $5,000 Teton outperformed my $7,500 Zesto Leto -- which has won multiple awards and received uniformly stellar reviews -- and the Teton serves double duty as a headphone amp, while the Leto is only a preamp. Good luck telling us that the Leto -- and virtually all other high-end audio equipment -- is overpriced.

OK, I am done egging on the troll.

n_maher's picture
There is no contention that a $110 FiiO model will outperform this one .
Congratulations on reaching the end of your audio journey at such an affordable price point.
HammerSandwich's picture

Tyll, would you please expand on the impedance issue with the LCD-3?

My understanding is that a high-Z output reduces the voltage reaching the phones. Obviously, this can reduce volume at all frequencies. Additionally, headphones with varying impedance versus frequency will display altered frequency response. (At impedance peaks, the cans will receive significantly more voltage than at impedance minima, unlike with a low-Z amp.)

How on earth does this behavior affect the frequency response of a flat-Z phone, such as the LCD?

Tyll Hertsens's picture
In muy experience, poor damping factor (High output Z, low headphone Z) will cause the bass to loose it's punch. When Skylab says it's bass light, that impression may be derived from poor bass control, even if it's at about the right level, subjectively giving bass less weight.