This is a review of the Decware SE84UFO2 Zen Triode Amplifier (USD 1499). Some of the following memories came to mind when working on and listening to this tube amplifier.

The first time I saw a tube amplifier was in the small electronics shop that my grandfather owned. It wasn’t a shop as such, it was more like a basement filled with old and broken TVs, radios, amplifiers, and even some electric guitars and basses. While I was there, at about seven years old, I remember the excitement of being in and looking around the store, with scattered nuts and bolts on the floor, the soldering iron on the table, and the feeling that something always needed fixing. Though my mind and eyes were always set on something else. Those “warm and glowy orange crystal lights” inside those amps and TVs were mesmerizing.

My grandfather would repair anything that people would bring him, even though he wasn’t trained in how to repair any of these things—a lifetime of experience and curiosity helped him to later master these electronics. He took pleasure in helping others. Born in Italy, and later becoming a US Citizen, was something he took pride in. He was in the Navy and even played in a military jazz band. I still have some pictures of him playing. I think my love of music also comes from watching him play and those amplifiers with their VU meters and warm glow comfort me in a way.

Decware Company

Decware is an American company, Steve Decker is the owner and lead engineer. He has made a name for himself for the high-quality products and affordable prices Decware offers. They have been building and perfecting this amp for over twenty years.

This amplifier was not sent for review. I read many rave reviews of Decware products and wanted to try one. Aware of the well-known months-long waiting list for their products, I wasn’t in any hurry. I purchased it in 2020, and two and a half years later it arrived. This was at the height of the pandemic, so I knew it would take a long time to get my hands on the amp. I would’ve appreciated more updates from the company to let me know that it was going to take three times the expected wait, nevertheless, I understood this was a strange time for everyone. When you order products from the Decware page (you only order directly from them), you are assigned a number and you can view where you are on the waitlist. Decware continually updates its page to let you know the journey of your amp (the process goes: on bench, parts pulled, testing, quality control).

When I received it, in a very nicely and carefully shipped box, I was very impressed with the looks of this amp, its solid build (17 lbs), two cool VU meters, with a solid wood frame, and the tubes and transformer, of course. Under the hood, point-to-point wiring, and no circuit board, a signal path with two resistors and one capacitor. The only caveat when purchasing was the meagre 2.3 watts of power, so I was intrigued as to what this highly praised amp sounded like. Also, there’s a lifetime warranty for the original owner. Decware builds speakers and headphone amps as well, hopefully, I’ll get a chance to try these in the future.

The Zen amp is a “here it is” type of design, without any flashy or slick colour finish; it looks like a design that came from an engineer who knows his craft, if that makes sense. One of the cool things that Decware does is the possibility to have add-ons to the amp: to the finish, the wood, the toggle switches and tone control (different prices that can add up the original price of course), and RCAs of XLR inputs (I chose RCA).

Decware comments “This is a pure Class/A single-ended triode amplifier with 2 high-current watts per channel and the ability to drive speakers between 2 and 16 ohms (my unit had a switch for both 4 and 8 ohm speakers). It features a potentiometer volume control (which I used during the listening period) and two pairs of input jacks making preamps completely optional. Also, it can be bridged into mono for around 6 watts. “Because of our floating output stage design, a pair of these amps can even be run as fully differential balanced monoblocks”

You can tube-roll but, there’s a unique sound from these tubes: One triode-wired EL84 per channel driven by a single 6922 and features 5U4 tube rectification. That said we use a superior variant of the EL84 called a 6P15P-EV from Russia. An extremely special tube with gold grids and super wide bandwidth giving a more transparent and neutral sound. From the same factories, we use a Russian variant of the 6922 called the 6N1P-EV. This is a warmer and nearly bullet-proof tube that exemplifies the term liquidity.

Specifications

Dimensions: 8.0" H x 8" W x 16.0" D

Circuit type: Single-ended Class/A Triode

Power output: 2.3 watts RMS x 2 or 6 watts RMS x 1

Input voltage: 1.5 volts for full output

Noise / Hum -79 dBU / -58 dBU@120HZ

Flat Response: 10 Hz ~ 80 kHz

Feedback: Zero

Rectification: 5U4G / tube rectification

Output tubes: SV83/6P15P-EV or EL84/6BQ5

Signal tube: 6N1P or 6922 or 6Dj8

Transformers: Decware UFO-wide bandwidth

Biasing: Self-Biasing / Cathode Biased

Resistors precision: WW/MF by DALE, VISHAY

Signal Cap Exotic Film and Foils

AC cord: Removable power cord

Consumption: 65 watts

Input jacks: RCA type Gold / Teflon

Output jacks: 5-way binding posts accept 12-gauge

Speaker dB/1w 89 dB minimum / 94 dB or higher is ideal

Warranty: Lifetime to original owner

Setup

I used the Mark Levinson № 5105 Turntable with the PS Audio Stellar Phono. For CDs, I have the PS Audio PerfectWave SACD Transport, through the Stellar Strata Integrated Amp/Preamp, for streaming the PS Audio AirLens (review forthcoming) and the Wiim Pro Plus.

It was interesting to compare several amps to the Decware. Along with the mentioned PS Audio Stellar Strata Integrated, I had the Vincent SV-500 Integrated Amplifier (hybrid), and another tube amp, the Margules I-240 (review forthcoming). For speakers, the Alta Audio Alyssa (a hefty 28 lbs each, with an impressive 2 1/2 inch “high speed” ribbon tweeter and a 6-inch midrange woofer, 87.5 dB/2.38 volts sensitivity and 4 ohms).

Listening Experience

I understand that when you read 2.3 watts of output power, some might flinch, I know I did, even so, trying out the Decware was a necessary endeavour. I’ve read reviews about the best pairings for the amp—speaker sensitivity is the name of the game they said, suggesting anything above 89dB is the way to go “otherwise you’re listening experience will suffer”. Well, my Alyssa only barely comes close to this number and I can safely say: I had no issues at all. Perhaps because in my listening, high volume is not as important as instrument separation and a clean and natural sound and in all honesty, I was not bothered by the low output. Many things surprised me about this little amp.

It took a while but after several months of daily listening to the UFO2, I heard a significant difference in its sound—burn-in is a must. So what’s the verdict? There’s a special sound in this amp. The first thing that you notice is that its timing is precise. Some might say “controlled” but more like that it gets the accurate tone of the music, it’s quick and spatial where it needs to be, and overwhelmingly clear. By this, I mean there’s never a lack of musicality in whatever genre of music I threw at the UFO2.

Granted you won’t get a lot of thumping bass, but the mids and detail more than make up for it. But its 2.3 watts does, I believe, have a plateau for the bass frequency. Many tube amps develop a sense of “rich or warm” sound, but I’d say the UFO2 does not, it presents more of a dynamically present and natural sounding amp with a resonant soundstage. A surprise was in its flexibility, and I mean this in a most complimentary way. The Decware eased in with every type of setup I could think of. The UFO2 sound was there regardless of the turntable, SACD transport or streamer.

When I put on the newly remastered double vinyl Siamese Dream by The Smashing Pumpkins, the sound took hold of the entire room, yes, difficult to believe but even in hard-to-drive and resonating distortion, this little amp had my friends and I rocking. A more subdued sound was also experienced with the box set The Art of Oskar Fried a remastered 78 rpm recordings to CD set, music recorded from 1923 to 1932, seemed to shine, not in a bright or warm tone, but on a neutral “as it was recorded” feel.

Conclusion

Are there things that I would change with this USD 1499 amp? Yes, I wish it had more inputs, that it had XLR connections (I ordered only RCA), and a little more bass. Also, I’d change the place of the inputs and speakers connections, but again, these are just more superficial wishes. The soundstage and precision of this amp more than live up to the hype. For twenty-five years Decware has been perfecting the quality of this amp for an audiophile sound far better than other amps at this price. No question this is a must-have on your audio wish list.

Further information: Decware