ampsandsound Kenzie Headphone Amplifier

General Information

Like many of our products, the Kenzie Headphone Amp evolved from our earlier designs – in this case, rave reviews about the SE-84’s headphone section. The inevitable question followed; why didn’t we build a dedicated headphone amp?

Why indeed? After some research, we came to the conclusion that the Kenzie amp using the much loved darling circuit was the right choice for us. The outstanding performance of the Kenzie Headphone amp is made possible with custom wound ultra-high quality output transformers providing amazing frequency extension. The Kenzie does not use a voltage network, and has more than enough power to drive even the most difficult headphones. We chose 32ohm and 600ohm to allow use with the widest variety of headphones.

The Kenzie Headphone amp showcases the transformers on the chassis to frame in the amazing 1626 tubes in all their single-ended direct-heated bliss. We have included an ALPS volume pot to allow attenuation and simplify the signal path… no preamp is needed.

The 1626 AKA Kenzie is one of the sweetest-sounding amps you will ever hear. The 1626 is commonly referred to as the poor man’s 300b; all the same great imaging, texture, and single-ended sweetness without the cost to break the bank.

The 1626 is a WWII era tube used as a transmitter tube in radar installations. The design is shy on pure output, but is overflowing with texture and drive, and is paired with a massive choke and robust output transformers for ultra-quiet operation. As with all of our products, parts selection was crucial during this build and each chosen not for price, but for best quality and synergy.

Latest reviews

Pros: Sound quality and price. (especially sound quality relative to price.)
Cons: ??? makes me want to build a full system?
An old friend and I have always had the "dilemma" of bridging the gap between what we want and what we need - especially when it comes to the finer things in life. Do you "need" to special order your BMW from Germany - probably not (although he decided to). Do you "need" to drink 30 year old scotch - probably not, or at least not all of the time (guilty as charged).

Enter Justin from ampsandsound, the Kenzie, and my introduction to the audiophile end of the spectrum for audio equipment. Justin took the time to describe what his company and products are all about - I was immediately interested. His passion is not only obvious when talking to him, but is visible in the attention to detail in his equipment.

I won't go into technical specs, all of that information is easily found elsewhere. I am very much a numbers and technical specs kind of guy, but after experiencing the sound quality and warmth of the Kenzie, the numbers and spec sheet no longer matter to me. I am hearing things in the music I have been listening to for years that I haven't heard before. The clarity, the warmth, and fullness of the sound isn't easily described with words; at least, words don't do the sound quality justice. The details I am now hearing has made my entire music library feel new again and I'm excited to listen through it all to find the "new" parts I've been missing.

Add the Kenzie to my list of items that filled a "want" and quickly evolved into a most definite "need". Cheers Justin for building an amazing product at an accessible price point such that my discussion of wants and needs will continue on.
Pros: Build quality, footprint, tone, looks!
Cons: Headphone jack placement (sort of).
ampsandsound has made quite a name for itself in the last few years. I remember the first time I saw pictures of Justin's classic designs and honestly, based on looks alone, assumed they'd never be in my realm of affordability (and in seeing some of his more recent releases, still aren't lol). I however, am very happy to say that I've recently been able to purchase one of Justin's personal units and I'll just say it... I'm out head-fi! Read on to see why this guy ticks every box for me.

The Breakdown:

The Chain:
MacBook Pro > Hugo 2 > Kenzie > HD58X, GH1, & PS1000

Test Songs (all ALAC either 16/44 or 24/96):

"Happiness" by Needtobreathe - HARDLOVE
"Strasbourg/St. Denis" by The Roy Hargrove Quintet - Earfood
"Grown Folks" by Snarky Puppy - Culcha Vulcha
"Living Hope" by Phil Wickham - Living Hope
"I Will Sing Jesus" by Highlands Worship - Jesus You Alone
"Jupiter, from The Planets" per Sir Adrian Boult and the LSO


Sound: In a word: tone. In discussion with Justin about the differences between his headphone amps, the word he used to describe the Kenzie first was the same. It's not particularly colored one way or the other, but because of it's no-feedback nature, can be swayed one way or another, whether by cables or tubes. In every experiment though, all of my listening selections were marked by a richness that was hard to deny. I don't know if I'd say smoothness, but to steal a word from the world of photography, everything had just the right amount of saturation. Thoroughly enjoyable with every song.

Bass: The low end on this amp is wonderfully clean and full. My headphone of choice is the original Grado PS1000, which has quite a bit more heft than just about every other Grado. The Kenzie strikes a great balance of thickness and control. With some amps I've owned, the PS can get a little too plump and cover the low midrange. Not the case here. From the kick on "Happiness" to the upright on "Strasbourg, St. Denis" everything in the bottom was tightly controlled yet unrestricted. It bears mentioning that I had the same experience with the GH1, HD58X, and an auditioned LCD3.

Mids: Sorry for the redundancy, but the word here is rich. I've had a MAD Ear+HD and Mainline during at the same time as the Kenz, so there's been plenty of tube-goodness to go around. The Mainline has a certain smoothness that was undeniable, and the MAD already has plenty of rep for it's tube-tastic flavor. Where the Kenzie differs (to these ears at least), especially with a few NOS tubes is that it maintains a noticeably better balance between smoothness and detail. The harmonized vocals from Highlands Worship's recent release were easier to separate but still sounded very natural and coherent. The same would apply to the horns and keyboards from the Snarky Puppy tune. So much fun!

Treble: Best balance in the upper range I've heard from a tube-design headphone amp. One of my make-or-break song for testing the upper end is "Grown Folks" by Snarky Puppy. There are trumpet/keyboard stabs throughout that are wince-worthy with the PS and less-refined or otherwise treble-tilted source gear. With the Hugo 2 alone, the upper end on those licks brushes up to the edge of my comfort. Running the Hugo into the Kenzie took just the slightest edge off, even at high volumes which is exactly where I like it to be. The MAD nor the Mainline accomplished that; they traded clarity for smoothness or sacrificed the latter for a little peakiness.

Soundstage/Imaging/Separation: Great! I've heard wider on a few occasions, but what I like about the presentation here is that the separation from left to right is strong AND the front to back is there. In my experience, usually you get one or the other. The Hugo alone offers TOTL separation, but adding the darling circuit really does something special with the front to back imaging. Well-done orchestral and jazz recordings really came to life when the tubes were added in!

Aesthetics/Build Quality/Accessories:
Su. Perb. Volume pot is super smooth. Plugs are tight. Fit and finish are all super clean. Frankly, I love the classic look and feel of this amp. Everything looks and feels well-made and I'll be honest, I feel a little bit like I've arrived with this piece of heirloom-quality gear on my desk. Thanks Justin for committing to your gear truly looking as good as it sounds!

Qualms: The only semi-qualm I have is probably predictable. Having the headphone jacks in the rear isn't super convenient. Yes I know it keeps the look clean and from a design standpoint, there's an advantage I'm sure. Just feels a little strange (or maybe just different) to have my Grados plugged into the rear with the cable draping over and between the exposed components. (Yes, I know the Encore solves this, but the Encore is beyond the bounds of my budget!)

JD's Tube Amp Ranking list: Kenzie > MAD Ear (upgraded) > Svetlana 2 > Mainline/WA6SE> Mjolnir 2 > Pan Am > WA6 > Elise/WA7tp > Ember II

Final Thoughts: All in all, the Kenzie is a beautiful, well-made, tone monster of a tube amp that deserves consideration from anyone in the market for an heirloom-quality piece of kit. For dynamic headphones, it's got all your bases covered (have heard it may not be there for hard to drive planars but I don't have any of those). I certainly am a satisfied customer and wholeheartedly recommend it! Thanks for reading!
Pros: Excellent tonality
Good clarity
Wonderful for high impedance headphones
Cons: Hum
Awkward headphone jack placement

AMPSANDSOUND KENZIE REVIEW

INTRO


Thanks to Justin of AMPSANDSOUND for sending me this amplifier for review as well as always being super kind and willing to answer all my questions.

The Kenzie is a little but serious amplifier made by AMPSANDSOUND that is the company’s first foray into the headphone world. The company first began making speaker amplifiers where it added a headphone amplifier output to one of it’s amplifiers. Later on they decided to answer the call for a dedicated headphone amplifier and now we are here with the Kenzie. It’s bigger brother, the Mogwai, came full circle being made with the intentions of offering more power for other headphones that the Kenzie is not ideal for but also the ability to power loudspeakers.

In another review I covered the Mogwai which is an amplifier I purchased because while in my stable next to the Audio GD-HE-9 I found it more to my liking. The Kenzie amplifier aims at more specialty and less versatility. As of recently I have had quite a penchant for high impedance and low impedance dynamic headphones. I wanted to hear how the Kenzie handled those loads and what this little guy is able to bring out of my music. I am very pleased to be able to share my honest opinion of the unit with you.

Do note that no tube rolling has been done during the Kenzie’s time here so all impressions are from stock tubes.

SPECS
Input impedance is 10K ohm with alps pot, .5v for full power
Input Sensitivity 520mV peek for full power out.

32ohm power: 200mWatts RMS @ 1khz, 20.5VRMS
Frequency bandwidth 20hz -3db to 12khz -3db full power
Frequency bandwidth 20hz -3db to 18khz -3db @ 160mw output
Noise on 32ohm tapp @ 500uV

600ohm power: 250mWatts RMS @ 1khz, 12.5VRMS
Frequency bandwidth 20hz -1db to 18khz -3db full power
Noise on 600ohm tapp @ 1.4mV

BUILD/DESIGN

Finish and looks


The Kenzie is a no frills, simple wood and fire amplifier. It is not nearly as flashy and impressive looking as my Auris HA2 SE but the build is solid and the while I think a glossy finish makes wood look more sophisticated it doesn’t go with all designs and personally speaking in this case I think it looks just fine.

Volume control

The Kenzie pot is smooth as butter with excellent resistance to ease of turn ratio. The pot is located in front of the amplifier while the inputs and outputs are in the back. I had no issues dialing in my ideal volume.

Impedances

600ohms output: This is where the Kenzie shines. A 300ohm output seems more logical but the 600ohm output worked beautifully with my HD650 and ZMF headphones. To spoil the review right here is fine to me as I am not sure you are here to read me carry about. Plugging my Atticus in revealed some of the best midrange tonality and realism I have heard under 2K easily. It opens the mids up like a uncaged bird with new wings.

32ohms output: Nothing to snuff at. Judging the Kenzie from using this output doesn’t really reveal what it is best at. It kept composure but sometimes I felt there to be a slight lack of dynamics and openness relatively speaking. For example I actually sometimes prefer the Mogwai with it’s 32ohm output, especially with planars due to it’s more powerful nature.

Tubes

YouSupplied Tubes:
Input tube: 12SL7 or equivalent
Output tubes: 1626 or VT-137

The options and variety of the chosen type of tubes for this amplifier are somewhat limited. I am of the believe that other tubes can alter the sound but if you purchase a Kenzie I wouldn’t have high hopes of doing a whole lot of tube rolling.

Noise

The 600ohms output’s wonderful sound comes with a small price, some slight hum when no music is playing. This is less loud than my Auris when using it’s high impedance output but still audible.

Power/Drive

Luckily there are a ton of headphones out there that the Kenzie can drive very well but with my HD6XX I am just a tad higher on the pot than I am used to, though there is plenty of headroom. Also I would stay away from hard to power planars like a T50RP Mod or HE500. Sure those headphones will sound good tonally with enough volume but they will also sound a bit compressed and flat in dynamics. My Odin is efficient but would like a little more power to allow it to open up. The Atticus and Eikon have no issues whatsoever, nor will your Utopia and Elear. I do believe LCD2, X, or 3 would do fine.

SOUND

The more amps I come across the more I have come to terms with the fact that in order to get the ideal sound you want you have to be selective of each component and know what meshes. That is obvious but in the case of the Kenzie, had I not had a high impedance headphone to test it with, I feel I would have deemed it good, great even, but not anything special compared to what I have on my desk now.

The Kenzie is a beautiful sounding amplifier. During my testing I found the Atticus to pair best with it so that is where most of the impressions below come from. Some pairings were not punchy, some were not; some pairings were amazing and some decent; yet none were a failure unless they called for lots of power. Even then tonally the Kenzie could never be to blame, sans a dismissable tendency to highlight the upper midrange of my HD650.

BASS

The sub bass of the Kenzie has good extension. For EDM and such the Kenzie has enough reach and presence in the sub bass for one as my self with a health appetite for low frequencies to settle. I often listen to a lot of the less mainstream artists like MNDSN or Eric Lau. On Eric Lau’s ‘Rhythm King’ I find the bass kicks to have excellent focus that cuts through the sub bass sustain notes even more than my Mogwai and Auris. It has a natural but quicker decay than either of them sounding a little more dry yet not solid state dry. Still and so it rumbles and growls just slightly less than either of them. It has less heft and bang than the beefier sounding Mogwai and is a little less hard and dense than the Auris. I previously said in another review that the Mogwai is tight and focused but the Kenzie reveals otherwise sounding a little more precise and defined but a little less heavy and thick. The Mogwai is a little less focused and could stand to be just a little tighter like the Kenzie. The bass is linear to my ears without any accentuations to speak of; it sounds neutral without any of the baggage that usually comes with that term. If you are looking for elevated bass I don’t think the Kenzie is the one and may even call it a hair below my personal ideal amount. On the Kenzie’s 600ohms jack I find the Atticus to sound more controlled and punchy than it does on most other amps I have tried with it. Also it is exceptionally responsive.

MIDRANGE

Straight up…the ‘King’ of mids for me so far in its price bracket. That is with the following in mind: Trafomatic Head 2(now outside of its price bracket at over 3K), the SPL Phonitors, stock Mogwai, Apex Sangaku, my Upgraded Mogwai (better mids than stock], Auris HA2 SE, iFi Pro iCan, Cayin iHA-6, Wolf Ear Makoyi, Audio GD-HE9 and other lower tiered gear. Now I can’t make that statement without disclaimers. Firstly, that is with the high impedance output where I hear a distinct openness for vocals that I have only really heard before on one other amp: the Audio-GD HE-9. The Audio GD had this aspect under its belt with even more transparency and a much blacker background but it was not combined with the proper amount of tone density needed to make it sound as realistic as the Kenzie does. Swapping from the SPL Phonitor E and I hear the same amount of clarity if not just a little less than the SPL, similar ‘hear through factor’, a very similar tonality and resolution, but more depth, body, resonance, and organics. The Kenzie does not sound overly thick, warm or syrupy in the midrange but full, resounding, and open. The Mogwai (upgraded caps) has a little more sweetness to it in the lower mids with the stock tubes but is less clean cut with it’s edges; more round and just as clear but not as open and vivid.

Listening to Livingston Taylor “Isn’t she lovely” I hear good dynamic range and the guitars have resounding tangibility. His voice is more believable on the Kenzie than my other amps. Hand percussion sounds bold and resolute with tangible and solid leading edges.

Now using my HD650, I find that I sometimes prefer the heavier and denser timbre of my Mogwai. I personally like to throw some meat on the HD650’s bones which is why I love it so much with tube amplifiers and in this case the Mogwai. I can also swap tubes and reel in a bit of its tendency to sound a little shouty to me at times with the Mogwai. However, the 650 still sounds more open and expressive on the Kenzie, and while it has a little less body, it is sounds deeper and better projected. I am sensitive to the HD650s upper midrange though so at times it is a bit much for me even on other amps so I listen with the Senns at a lower volume because the Kenzie can lightly highlight this aspect.

The lower midrange sounds flat to my ears without any extra warmth. The middle midrange is spot on and the upper midrange or higher end of the middle midrange is just barely accentuated.

TREBLE

I find the Mogwai and Kenzie very similar in treble performance. The Kenzie has excellent resolution just as the Kenzie does but I feel the Mogwai is a bit more raw and resolving up top than the Kenzie. I can hear the echo trails of cymbals better on the Mogwai over the Kenzie just slightly. The textures of the Kenzie are not smooth or dull and provide decent bite even compared to some solid state amps. The balance is pretty even without any hard spots in the lower treble. Extension seems a very small bit better than the Mogwai which leaves me with no real complaints. I find the SPL Phonitor to have just a little better extension than the Kenzie. The upper treble has more presence on the SPL Phonitor E that sounds a little more neutral and evenly balanced to my ears but not by much at all.

PERFORMANCE

The Kenzie is a less punchy and snappy sounding amplifier than my Auris HA2 SE that drives rhythm a bit better regardless of impedance due to its harder bass and excellent dynamics but with a high impedance headphone the Kenzie is not far behind and sounds more open with better depth to its images. I still feel the Auris is a better all arounder because it can do some planars decently and regardless of the pairing it exhibits these traits whereas the Kenzie is a little more finicky with the headphone you plug into it. But the right headphone into the Kenzie sounds like you are unlocking the paid for version of your favorite song instead of listening to Spotify it is also more resolving than the Auris.

The Micro-Dynamics are pretty good on the Kenzie but the way the midrange blooms, swells, and drops in volume makes it’s Macro-dynamics take precedence as one of it’s notable attributes. I found my Atticus, and HD650 to sound more dynamic in the mids on the Kenzie than my Auris, Mogwai, and the SPL Phonitor but the Odin and Meze to sound more expressive on the others over the Kenzie. Do note though that the Kenzie still had better hear through factor with them and still was decently charismatic with the Meze Classics as there is no sense of compression with the Kenzie.

Soundstage on the Kenzie is actually smaller than my tweaked Mogwai, mostly in width but depth seems to go to the Kenzie but just a hair. The Mogwai(with upgraded caps) soundstage is more even, with less height while the Kenzie has better separation since it sounds less wet and also has slightly better height. I prefer the soundstage of my upgraded Mogwai overall though. I feel my Auris is just a bit better at layering and making the images sound emboldened in their positions but the soundstage sizes between the two (Kenzie and Auris HA2SE) are similar. All on it’s own I feel the Kenzie is pretty good with staging that is naturally holographic.

Attacks and decay are fairly good having me wishing to re-evaluate my Mogwai which (again) is comparatively slower in decay and less sharp with attacks. The decay and tone density of the Mogwai give it a thicker, more lush, and full sound. The Mogwai sounds more round and smooth in the bass and midrange attacks.

Piano keys wallop with good timbre and body but have slightly less physicality to them than the Mogwai or Auris does but not by much. Tone Density is actually a little more on the Auris and Mogwai so they sound just ever slightly more visceral than the Kenzie. Specifically in the bass where the Auris HA2 SE sounds harder and the Mogwai heavier. While just slightly less dense the Kenzie never sounds thin to my ears, especially compared to solid state amps.

Resolution is pretty good on the Kenzie. Small details are something I find it to pull out better than Auris HA2 SE by just a bit. Given they are the same price almost I would have to say that the Kenzie has slightly better sound quality.

PAIRINGS

ZMF ATTICUS – The best I have heard it so far. Sure the Auris HA2 SE gives it more drive and a sense of nuance but it doesn’t make it sound as open and still the Kenzie is punchy making my Atticus sound crisp and defined. It is a very engaging pairing as well and is able to reveal how lively and potent the Atticus can be on the right amp.

SENNHEISER HD650 (MODDED) – While it plays a little less gently with the upper midrange of the HD650 it still sounds really good with it. It gives it good punch, an expressive sound, and highlights its strengths; taking it to new heights.

KENNERTON ODIN – This pairing has good tonality but is not really as dynamic as I am used to hearing it on my Mogwai. My Mogwai opens the Odin up more and gives it better body. Also on my Mogwai the Odin sounds really natural and just as clear as the Kenzie. I find the Odin easy to get it to sound loud with a lot of room on the pot left on the Kenzie at just 11 o’clock on the dial for those songs I want to turn up but it sounds compressed compared to the others on my desk.

MEZE 99 CLASSICS – While I find it a good pairing, I don’t feel the Classics reveal what the Kenzie can do, or vice a versa. It is natural and the drivers don’t sound like they lose focus but it is only average at making the Classics sound intense and I feel like the Mogwai and Auris make it snap a little harder

FOSTEX T50RP – My mod has a bit extra in the presence region and the Kenzie is not powerful enough to cut it. Sorry it’s just not.

CONCLUSION
It is possible that there may be some better sounding headphone amplifier at 1700 for my favorite closed back – The Atticus – but I haven’t heard it. The Kenzie has very good tonality and realism from pleasant tube distortion and is a little more clean cut when handling transients than some of the other tube amps I have heard around it’s price. I think it works well for high impedance headphones and does above average for low impedance headphones as well.

To put it this way may help understand the Kenzie. When I try low impedance headphones on the Kenzie it is not that I do not think they do not work well, in fact I find the Kenzie to be competitive with any amplifier around its price unless you need lots of power. But the way it opened up my 6XX and especially my Atticus was special in synergy. Upon first plugging my Atticus in the Kenzie I wanted to get rid of my Mogwai so I could have one but I prefer my planars on the Mogwai and to a lesser extent the Auris and since hardly any amplifier does it all then synergy is the name of the game. It’s obvious that I like the amplifier. It is tough for me to critique it’s sound quality and I have already been recommending it. If you are building a rig around anything like a Senn, Beyer, ZMF Dynamic, and even some low impedance dynamics I think the Kenzie is worth considering for sure.
Originally posted here at earphiles.org
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To really hear the Kenzie at its best you should replace the stock 12SL7GT input tube with a 1960 vintage Telefunken "Diamond Bottom" ECC801S using an adaptor readily available on eBay. If you can find them the rarer Tung Sol 1626 also better the NOS RCA the Kenzie ships with.

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