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Unison Research Triode 25 Integrated Amplifier: Quick Take

Italians make beautiful things. The Unison Research Triode 25 Integrated Amplifier ticks off every box and then some. Our early thoughts.

Unison Research Triode 25 Integrated Amplifier with Cage and Remote

I have long held the belief that audio components reflect the culture of the people behind them; the Italian obsession with design, craftsmanship, beauty, and quality is reflected in many of the products that are produced by brands like Audio Analogue, Opera, Gold Note, Sonus faber, and Unison Research.

Having grown up in the pizza business and on the border of Toronto’s largest Italian neighborhood, my soul has always felt very much part of the Azzuri. Three Italian World Cup jerseys hang in my closet from the days when this Jewish nerd played football with the Italians, Croatians, Germans, and Portuguese and everything became very personal when global football supremacy hung in the balance.

Bitondo’s Pizzeria, Toronto, Canada

Italians care about the little things that make their cars, clothing, shoes, cuisine, wine, firearms, and Hi-Fi components very different; strip away the design beauty, and one is left with products that not only strive to be unique, but are often temperamental, seductive, and quite emotive.

The Unison Research Triode 25 Integrated Amplifier is all of those things.

Unison Research Triode 25 Integrated Amplifier Lifestyle Angle
Unison Research Triode 25 Integrated Amplifier

II Magro

When unpacking the Triode 25, one is almost immediately struck by how solid the amplifier feels and the quality of the craftsmanship; the solid wood front panel is even more luxurious than the photographs convey and the tube cage almost begs to be left on to keep prying fingers safe from the heat produced by the tubes.

The custom hand-wound transformers do not get hot to the point that you can’t stroke their top cover in the way you would imagine softy caressing Sophia Loren’s magnificent face with your fingers. That didn’t feel wrong or dirty to say.

Unison Research Triode 25 Integrated Amplifier Top Angle

The 4 EL34 output tubes are hand selected by Unison Research and have proven rather reliable; which is a really good thing right now when tube availability is sketchy and prices have increased rather dramatically.

A quad set of NOS replacement tubes will set one back a frightening amount of money; and that was never the case before with EL34s.

Having owned 5 tube amplifiers over the past 25 years that used them, I am very aware of the replacement costs involved and it is sad to see what was a very affordable tube become an expensive proposition.

Unison Research Triode 25 Integrated Amplifier Top

The Triode 25 can be switched from Pentode to Triode mode at the flick of a tiny switch on the top plate. You can do this while listening to music and there shouldn’t be any issues but I would not advise doing it as a regular practice because I don’t see the switch lasting if you get too aggressive with it.

Switching between Pentode and Triode changes the presentation of the Triode 25 and not just from a power perspective. In Pentode mode, the power output is 45 watts per channel, and the Triode mode delivers 25 watts per channel.

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Brio Bottles
Brio Italian Cola

There is an IR sensor on the front panel hidden behind a cover that is somewhat fragile and I am willing to bet 2 cases of Brio Chinotto that someone will think that it is a power/standby switch and depress it. Do not touch it.

The rear panel is very neatly laid out with 4 sets of analog inputs (CD, Tape, AV, Tuner) and 1 USB input if you order that version of the Triode 25 that comes with an internal DAC.

There are subwoofer and tape outputs as well which makes the unit quite useful from a connectivity perspective.

The front panel includes the power on/off switch, and two very hefty control dials for selecting sources and controlling the volume. The Unison Research Triode 25 is built like a tank and everything about the fit and finish is first rate.

Did I mention that it sings like Louis Prima when you are nice to it?

Unison Research Triode 25 Integrated Amplifier Rear

Technical Specifications:

  • Output Stage: Push-pull, ultralinear, Class-AB
  • Output Power: Approx. 45 watt per channel
    Pentode configuration
    Approx. 25 watt per channel
    Triode configuration
  • Output Impedance: 6 Ohm
  • Input Impedance: 47 kOhm / 50 pF
  • Negative feedback: 5 dB or 1.8 dB
  • Valve complement: 2 x ECC83 (12AX7) 1 x ECC82 (12AU7) 4 x EL34 (6CA7)
  • Weight: 45 pounds

The biasing system requires you to flip a switch and turn a tiny dial until the black wiper is dead center. It took under 20 minutes to connect all of my sources, loudspeaker cables, install the tubes and bias them, and let the amplifier warm up.

Musica Dolce

To say that the Unison Research Triode 25 sounds completely different in Pentode/Triode mode would be overstating it; there are certainly differences but the overall character of the amplifier does not change.

There is nothing warm or syrupy about the Triode 25; it does not roll-off at either extreme and the midrange is not wonderfully lush at the expense of everything else. If you are looking for a very warm sounding tube design — this is not your amplifier.

The Triode 25 in Pentode mode, reminds me of some of the more recent Audio Research designs, but with less power on tap. It is wonderfully clean and transparent sounding with excellent detail and top end energy.

The midrange has just enough color to betray its valve roots, but it never allows itself to get too soft or organic sounding.

Amy Winehouse’s “Valerie,” off her BBC recording is pushed forward of the loudspeakers but she never loses her edge or grittiness and the Triode 25 doesn’t try to make everything too thick or sweet when it doesn’t need to be.

When I switched to Triode mode, everything sounds more delicate and sweet, but also at the expense of low end impact and overall dynamics. Winehouse was certainly front and center in both modes, but Pentode felt more accurate and true to the source material.

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Listening to Eric Dolphy, Donald Byrd, and Joe Henderson, the Triode 25 demonstrated that it can really swing, and that it has a lot of top end energy and airiness with the right pair of loudspeakers.

The tonal balance certainly favors loudspeakers that are warmer and more reserved in their presentation; the 3050i can be boring with the wrong amplifier because the treble lacks some bite — but all of that changes with the Triode 25 that lights a fire under its tuchas and makes vocalists more palpable.

Horns have more bite but also more natural sounding decay and that only makes you put down the pen and listen as the notes slowly vanish in the space between you and the loudspeaker.

Marantz CD60 CD Player Silver Angle
Marantz CD60 CD Player

The Marantz CD60 is both warm and transparent sounding and it definitely tugs at the heart strings while listening to Tony Bennett and Amy Winehouse, or Nick Cave profess their love. The imaging could be tighter, but I would chalk that up more to the CD player than Triode 25.

Having only used the Triode 25 so far with the Q Acoustics 3050i, Wharfedale Diamond 10.1s, and a pair of Opera bookshelf loudspeakers (under review), I have only begun my journey with this rather special amplifier.

I will have more to say next week, after trying the Triode 25 with the new Pro-Ject X2 B Turntable, Marantz CD60/Holo Audio Spring 3 KTE DAC, and two phono stages that I took out of storage because this amplifier has me very intrigued.

Unison Research Triode 25 Integrated Amplifier Angle

The Unison Research Triode 25 is certainly not inexpensive at $4,499 USD, but it is proving to be a very strong performer that keeps getting better with each passing day.

This one might be a keeper.

Viva Italia.

For more information:

Related Reading:

Vincent SV-737 Integrated Stereo Amplifier Review

Best High End Integrated Amps Over $4,000

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  1. Mike Little

    September 1, 2022 at 2:21 pm

    Great review made even better by the Brio reference, brings back fond memories of the home town pizza shop in the 70’s.
    Do you think this has enough muscle to happily drive the Sonus faber Lumina 1’s at 84dB sensitivity?

    • Ian White

      September 4, 2022 at 7:13 pm


      The Unison in Pentode mode can drive them rather easily but the price difference is enormous. You could buy 4 pairs of the speakers for the price of the amplifier.


  2. ORT

    September 2, 2022 at 2:35 pm

    Hmmmm…At 84 dB I would say the Luminas are about as sensitive as an ex-girlfriend. She may well be loverly but in truth it’s likely more a match made in Hades.


  3. multidirectional

    September 12, 2022 at 5:06 pm

    Touche. Outstanding arguments. Keep up the amazing spirit.

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