General Information
I recently received a Kenzie headphone amp from ampsandsound and wanted to share my impressions. Packaging was among the best I have ever seen always a good sign.
I do most of my headphone listening streaming Qobuz and locally stored files using the Audirvana player. My signal chain is PC > Yggdrasil Analog 2 > ampsandsound input transformers > Kenzie > Sennheiser HD800S phones.
The HD800S are my reference phones. I had been listening through a Vali 2 while waiting for Justin to build my Kenzie, which only took a month including shipping. Compared to wait times from other custom tube amp companies that is quick!
The Vali 2 is a good starter amp for the HD800S. If you have never heard a top of the line tube amp you could be happy with it. 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. Listening with 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.
There was an upper treble sibilance with the Vali 2 that is gone with the Kenzie. Midrange is wonderfully accurate with plenty of air around voices and instruments. I have no problem following complex bass lines. Treble is extended and pleasing, and on well recorded pop I can follow the drummer as he plays. It is easy to listen deeply into recordings.
The base Kenzie comes with WWII NOS RCA 1626 power tubes and a Sylvania 12SL7GT for input. While not required you can roll tubes. After a few months of tube rolling I found the ideal input tube for me is a 1960's Telefunken "Diamond Bottom" ECC801S (adaptor needed available on eBay). While not cheap this tube is well worth the cost (about $220.) The top image shows the replacement tubes.
As good as the stock 12SL7GT tube is the ECC801S lifts a veil providing more detail with better imaging and soundstage. The Telefunken takes the sound quality up to a level significantly higher than the stock 12SL7GT. If you can find them, replacing the RCA power tubes with the rarer Tung Sol 1626 provides better bass and even better imaging.
Over the time I have owned the Kenzie I have tried many input and power tubes, including the newly recommended 12B4A / 5755 power / input tubes. The combination of the Tung Sol 1626 power tubes and Telefunken ECC801S input tube provides the best sound I have heard from the Kenzie to my ears. A very good matched pair of WWII RCA 1626 are a close second to the Tung Sol 1626 which have become rare,
While the outside of the Kenzie is beautiful you can also see that Justin does top shelf interior construction and wiring:
Along the way after discussion with Justin at ampsandsound I also added input transformers built into a small outboard box. Here is an image showing the input transformers with the stock tubes.
The input transformers lower the noise floor of an already very quiet amp and improve bass slam and definition. Nice to know you can buy a base Kenzie and add the input transformers later if you choose.
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 fully optioned Encore at $2545 with input transformers built in and upgraded coupling caps. The Encore also has 2 inputs and 1 variable out to be used as a preamp. Headphone jacks are also moved to the front.
If your budget is under $1800 don't think you are just getting a starter amp buying a base Kenzie. I consider the $1650 a bargain actually. When most folks think of a reference amplifier for Sennheiser HD800S headphones they only consider the Zana Deux S or DNA Stratus. I think it is time the ampsandsound Kenzie and Encore are also given consideration.
Justin is great to work with and quick to answer emails. I consider the base Kenzie one of the best sounding tube headphone amps you can buy under $1800. Adding the input transformers and 1960's Telefunken ECC801S input tube improves the Kenzie significantly into what would be an end game tube amp for many