Kenzie headphone amp review (ampsandsound)

I recently received a base Kenzie headphone amp ($1700 shipped) from Justin at ampsandsound and wanted to share my impressions. Packaging was among the best I have ever seen always a good sign.

Now I do most of my headphone listening through Tidal HiFi some MQA and locally stored files. My signal chain is PC > AudioQuest Diamond USB > Eitr > Blue Jeans S/PDIF > Brooklyn DAC+ > Kenzie > Sennheiser HD800S phones. You don't see all the chain because some components are on the other side of the laptop on the right side of my work desk.

The HD800S are my reference phones and will be until Sennheiser comes out with something better under $5000. I had been listening through a Vali 2 while waiting for Justin to build my Kenzie, which only took a month including shipping.

The Vali 2 is a good starter amp for the HD800S. If you have never heard a boutique tube amp you could be happy with it.

No disrespect to Schiit but I just spent a morning listening switching between the Vali 2 and Kenzie and the Kenzie outclasses the Vali 2 in all respects.

The first thing I notice is soundstage and imaging. While the Vali 2 soundstage is between the ears and shallow with the Kenzie the soundstage is deep, three dimensional and extends outside my head with good masters. Not all the time mind you but it does happen. This is why I use HD800S!

There was an upper treble sibilance with the Vali 2 that is gone with the Kenzie. Midrange is glorious with plenty of air around voices and instruments. I have no problem following complex bass lines.

Treble is accurate and pleasing, and on well recorded pop I can follow the drummer as he plays. It is easy to listen deeply into recordings.

I have not found anything to fault yet will update if I do. With Kenzie you have the choice of the base Kenzie at $1650 or the full on Encore at $2545 with input transformers and upgraded coupling caps. If your budget in under $1800 don't think you are just getting a starter amp. I consider the $1700 I paid well spent, a bargain actually.

Justin is great to work with. Since I only use 300 ohm phones he ordered a transformer with 32/300 taps:



Yes, the HD800S sound better from the 300 ohm output if you were wondering. After I was impressed with the base Kenzie we struck a deal for Justin to build me a set of input transformers in a separate box that would give me sound closer to the Encore. Everyone automatically thinks DNA or EC for high end amps for HD800. I think ampsandsound should be added to the short list.

 

I would think the 800S would sound better from the 300 ohm transformer tap than the 32 ohm tap - much closer matching.

This seems like a simple design, but I think it might defeat the purpose of using cathode follower 6AS7 power tubes when you have to use a transformer output.

Do you know if this design has an input filter choke?

 

You would have to ask Justin. He may see this as he is a forum member or just PM @ampsandsound

 

Having owned the Kenzie for approximately 3 months, I’d thought I’d take a moment to offer a review.

First off, my Kenzie was purchased from a fellow member here, and was built with the upgraded cap option. Originally supplied with the stock tube set, additional tubes were sourced and provided with the sale, and subsequent input tubes have been purchased by me. Most, if not all, of my impressions will be based on experience I’ve had with non-stock tubes.

Gear(all owned by me):
Mac Mini > Audivana+ > [Gungnir Multibit G.5 / Eitr.Modi Multibit] > Kenzie > HD6XX-K / Atticus

Most of my comments will relate to HD6XX pairing, as this is more widely used here.
​

Spoiler: Pics

TL;DR
The Kenzie is a well-made tube amp offering a balanced, romantic tonality. Shy in bass dynamics, and somewhat-narrow but deep soundstage that at times can be a bit dense/or veiled. Stock tubes are good, but rolled-tubes can yield positive improvements. Tone centric amp, with technicalities more as a secondary focus. Pairs well with Senns. & ZMF dynamics (probably others, but no experience so YMMV). Best paired with balanced, high resolving sources; those with darker, more “musical” characteristic may overly accentuate the limitations of the amp.

Fluff mode on: Has an innate addictive sound that paired well (Gungnir Multibit/Atticus) is incredibly appetizing. It’s synergy at work = complete utter subjectivity, but hot damn it’s seriously yummy.​

Quick Notes on Build Quality and Ergos:
Ampsandsounds builds a quality product. I’m sure you can see in the promo marketing; but in hand, the fit and finish really are quite impressive. It’s a substantial little amp, that has a classic/traditional tube-amp look. I dig it. The ergonomics are a bit funky. Placement of the source input are at the back of the unit, nestled together with the headphone outputs...at the back. As I said, a bit funky, but not really a deal-breaker. Subsequent chassis revisions by A&S on their newer models have moved the outputs to the front.

Tonality
The Kenzie’s tonal balance seems fairly balanced, with a slight mid/upper-mid emphasis. It does not exhibit the classic tube sound (ultra lush/gooey/wet/euphonic), but has a well-mannered SS-like presentation, very similar to my Black Widow. Bass is a tad light, more in dynamics then in quality, as the bass still has good substance, extension and texture. Treb. has good air, and resolves decently, with substantial gains with various input tubes. Mid emphasis make for a romantic, if slightly hazy/veiled presentation that is incredibly subtle and near negligible unless compared to more-open, clearer sounding gear. My Black Widow 2, as a comparative, immediately shed light on the veil. Others have called this a “flavor” with the “mids being rich”, and I would agree to a point, that the tonality and it's presentation are something to be acquired and savored. It’s not the clearest, or most resolving or analytical of amps, but subjectively, it does tone right.

So, I’ll pause here. If tonal balance is all-important to you, then the amp should absolutely be on your short-list. This doesn’t mean the amp falls apart in technicalities, far from it. There are just areas that are not as good as they could/should be. I may be nitpicking, but with $$$/value proposition of $1500 plus amps, I’d want it to nail both the sound that I’m looking for and it’s presentation.

Notes on Technicalities:
The Kenzie has a fairly neutral headstage, in forward-back placement. SImilar to the BW and more laid-back than Jotunheim. Width is decent, but not as wide or open as the BW, yet more wide than the Jot, perhaps by a hair. It has good depth, and decent height, but layering is not as delineated and the overall 3D space presents a touch flat.

There’s good resolve, and minute details come through in good proportion. As I mentioned, the Kenzie does seem to have a slight haze/veil/romance/richness to its sound, so while fine detail comes through with great clarity on the Jot, with the Kenzie it can be a bit foggy and a slight volume attenuation is not out of question - at least while trying to listen critically. The details are not up-front, but reserved and available with some effort. The BW on the other hand has a clarity and openness that resolves fine detail and plankton with little effort - not jumping out, as I sometimes experienced with the Jot, just more relaxed and lays them out for easy appreciation.

Dynamically, the Kenzie does well. Drastic, macro-dynamic shifts are good, with low-level to high contrasts clear and distinct. Compared to the BW, the Kenzie does seem to have a slight compression, as the volume shifts seem narrower in scope, the differences between loud and soft being of different scale. That said, there still presents a good contrast, perhaps a smidge better than Jotunheim.

Of the three amps for my comparison, the Kenzie hits softer and has less slam than the rest. It’s just doesn’t have the thump that you can feel. I know that the BW slams hard, but the Kenzie is comparatively light to the Jot, which is the least amount an amp should slam in my opinion for a true genuine sound reproduction.

The Kenzie has good micro-dynamics, conveying realistic and natural reproduction of instruments and vocals. Subtle guitar picking and wind instrument tonguing sound genuine, with good articulation and nuance. Here’s an area the Kenzie does seem to step ahead of the Jotunheim, with capability of producing a genuine sound experience. The BW and Kenzie are neck & neck here.

Fluff mode on: This is where I feel the magic of the amp happens, subjectively; and when paired with the Atticus, can really eek out every bit of nuance in a given track. The Atticus just seems more capable, better suited, and dialed-in with the Kenzie. ​

Transient response is good, but not better compared to the BW, with decent bite, but during heavily dynamic, busy passages, the Kenzie can lose a bit and smear. I perceive better control with the BW and Jot due their increased clarity; having a better sense of the notes and their attack/decay (space between). It could also be both exceed the Kenzie's power output and have a better grasp on the dynamic drivers(?). It’s a minor complaint and one that I find occurs so rarely with my given music preferences.

Notes on tubes:
Rolling input tubes provides a subtle change to the tonal balance of the amp. I picked up NOS Sylvania 12AT7 (adapter needed) after a recommendation from another member here, and found it to be a perfect blend of bass extension, tonal resolve and air. Initially, I ran the stock RCA 1626s for the output tubes, and while decent, it wasn’t until my seller’s suggestion that I try the included Tung Sols. These tubes opened up the stage and dropped the veil substantially. I could still perceive it, but it was greatly diminished, and brought the performance perceptively up to the level near the BW.

Source combinations:
From what I’ve read of others, and my personal experience and knowledge, I’d feel comfortable saying that the Kenzie best suits resolving, decently dynamic (with punch) sources. The Gungnir Multibit brings that full bass and wallop that the Kenzie desperately needs, coupled with very good staging and sense of space. The Modi Multibit, though decently resolving, is a bit too dark; with Kenzie's limitations it could lead to a diminished sense of detail and space.

…let me sum up:
I really like the Kenzie. Though it has some quirks, and misses a bit technically, the tonal balance and pairing with my current favorite headphone (ZMF.A) is spot on. Could I personally own the amp alone? No. I would need something with some punch, and the amp does have limits with what headphones it can drive; yet if you are currently running higher Z Senns. and/or ZMF dynamics, you really should give it a demo. Rolling output tubes helped a ton with the shortcoming in openness and veil, and various inputs provided subtle but substantive changes with tone extension and presentation. It’s a solid contentender in the category, but does come with some faults, that at its price-point, miss the mark for me. I honestly would say the Kenzie is only 6.25%* back from the BW, really not so substantial a difference. It’s more about what you value in the amp, tone or technicalities. I for one want a blend of both. The Kenzie is close.

This said, I’m very eager for more from both EC and A&S. Next for me is a ZDS (hopefully), but Justin’s new Mogwai SE has me thinking. But one amp at a time.


* Complete subjective fluff-talk.

 

Justin recommends 1626 or VT-137 for the two output tubes so I read your comment on output tubes with interest. Exactly which Tung Sols are you using for the two output tubes and where did you buy them from please? Thanks for the input.

 

Plain ol’ 1626 Tung Sols, provided and recommended by the member that sold me the amp.

I believe he sourced them from eBay.

 

Thanks! My Kenzie came with RCA 1626. Are you recommending Tung Sol 1627 or 1626?

 

Typo. 1626s.

 

Thanks. I have a set of outboard input transformers on the way (available as an option on the Kenzie Encore) and should be able to give impressions by end of next week. Supposed to add definition and slam.

 

That is an option, but two points came up for me:

1. I asked Justin for a set of outboard input transformers, but for the price, it just didn't seem the ideal solution. At that point, as might as well pick up a Mogwai (that has better dynamics and close-to Kenzie tonality), or just buy an Encore. Hell, Justin even advised that the differences for the Kenzie would be minimal, and that I'd be better suited using the money for a new set of headphones.

2. Daisy-chaining the source signal with outboard gear prior to the amp just doesn't sit right with me, and while I'm sure A&S knows what's what, the Kenzie was not designed and optimized to use the outboard input transformers. Their use was to demonstrate their capability added to the topology of a finished amp, and I'm sure other nuances went in to make it right.

Slam and a lower, quieter noise floor is what I understood the benefit to be. Hopefully it improves other technicalities as well, otherwise if your already spending $400 for the outboard transformers, it's really not terribly difficult to budget another $400 and step up the Encore.

 

Well hell yes, I made a mistake not going for the fully optioned Kenzie Encore ($2545) when I had my Kenzie ($1650) amp built. However I am not selling the Kenzie at a loss now so the outboard transformers will have to do for the time being.

 

I would only say it’s a mistake if you feel the Kenzie is missing something and feel compelled that the Encore is the solution, or would have provided what it is your missing.

I find subtle fault in the Kenzie, relative to my other gear, and while I’d like an amp that offers better technicalities, I wouldn’t want to change it.

Hopefully the input transformers get you there.

And one persons mistake is another’s path to find what sound they want - I’m still on that path.

 

Allegro,

Hope you enjoy the set coming your way. Super cute and tidy. I wish I could add input transformers to the Kenzie. In my attempts to make it as small as possible, I shot myself in the foot. At the time I wasn't the biggest supporter, wasn't my area of focus. Since then, Ive taken time to try various caps and input transformers. At this point, I use input transformers in all my systems as I really enjoy their addition.
As a general rule, I try to suggest having new headphones or music before other ideas for upgrades because ultimately Id like the gear to fall into the background the let the listener find the music and themselves.

 

Sometime soon, Ill post my overwhelming love and use of transformers in my system.

 

You certainly accomplished it with the Atticus, it's highly addictive, immersive, and engaging.

 

Received the input transformers. They are enclosed in a small black aluminum box with silicone feet. Nicely made!



First impressions listening over a few hours are very positive. I hear more slam and definition in the bass. What I did not expect was to hear more air around instruments and voices in the midrange. Listening to Emmylou Harris' "Wrecking Ball" was a good demonstration of how the transformers help in hearing details in bass.

I have taken the transformers in and out and preferred sound with them in the chain each time. Budget aside, if I was considering buying a Kenzie today it would be an Encore with the input transformers and upgraded coupling caps no doubt.

 

I gotta point this out, but the 300 ohm is a worse match for keeping the FR from changing due to the damping effect. The 300 ohm tap is *literally* 300 ohms of output impedance to a 300ohm headphone. The 32 ohm output impedance to the 1:8 impedance ratio. Though, if you enjoy the FR change (and many tend to enjoy that with this amp,) than it's just fine. But I thought I'd point that out.

 

I prefer my Senn from the Kenzie's 32 ohm output, and the Atticus seems to like the 600 ohm on my amp, subjectively. I'd like to try the 300 ohm, and inquired with Justin on swapping, but alas, the costs....

I'm glad the input trasformer box is working for you @allegro, it's a much smaller box than I had anticipated. Thanks for posting a pic for reference.

 

Right. Never want to go lower. Might go poof.

I've been messing with OTL amps for too long. Forgive me.

 

Before I had Justin build my Kenzie we discussed output taps and decided on 32/300 ohm since I have no plans to buy 600 ohm phones in the future. Pretty much settled on the 300 ohm HD800S. I asked him about the 1:8 rule and my amp and he replied:

I noted no noise on either the 32 or 300 ohm taps even before addition of the input transformers.