In case you are not familiar with the name Unison Research, it is an Italian company in business for some 20 years or so at Treviso, a municipality just to the north of Venice, with a well earned reputation for producing some excellent hifi components. Dominic Marsh has a play with their Triode 25 valve amplifier.


At first glance this amplifier looks positively handsome.  The sample supplied for review sported a real Cherry wood fascia which I found rather attractive and a welcome change from the ubiquitous black or silver finish.  The remainder of the chassis is painted black however and as a foil to that the valve bases are inset into two polished alloy heat shields which extend from the front panel in a sweeping arc upwards, meeting the top plates of the transformer covers.   A rather substantially built chrome plated valve cover cage is supplied, removed by slackening off four Allen bolts and sliding the cover along keyhole slots in the cover’s base plates to quickly release the cage.

For those that don’t own or know how to operate a multimeter, or have the confidence to go poking around within the internals of a valve amplifier to adjust the valve bias settings, Unison Research have thoughtfully provided a simple yet effective way of adjusting the bias current settings.  Betwixt the valves on the valve base level there is a simple voltmeter and a potentiometer that makes setting the bias child’s play and completely safe, even for the most novice of owners.  The review sample needed no such adjustment but I took the time to read the owner’s handbook and it seems simple and painless.

The end user has a choice of power output modes between Pentode and Triode.  I won’t go into details of how the two modes work, save that Pentode mode gives a higher wattage output with a slightly less refined sound whereas Triode mode has a lower output wattage, but has greater detail and clarity.

Front panel controls consist of a machined alloy rotary knob to the left which is the source selector and an identical rotary knob for volume control to the right of the panel.  Between the two in the centre of the front panel is a toggle on/off power switch aligned horizontally, beneath which is the remote control sensor window.

To the rear we find from left to right, an IEC power inlet socket with integral fuse holder, the fuse rating depending upon mains input voltage, the value thoughtfully printed on the transformer cover above.  Then we find a set of four speaker binding posts, able to accept 4mm banana plugs, spade connections and bare wire.  There is no biwire facility or catering for more than one pair of speakers.  Next we see a row of single ended RCA connections, namely  SUB out, TAPE out, TAPE (Input), AV input, TUNER and CD.  To the right of this is a blanking plate marked “USB” which would have a USB connection if the module is fitted.

It is supplied with a remote control handset.

Retail price is £2,600.00 at the time of review.


They say that EL34 valves have a sweet sound to them, but that has more to do with the design implementation of the circuitry, especially in the output transformer quality rather than a mythical inherent sound to the valves per se, as I have been less than enamoured with some EL34 amplifiers I have listened to in the past.  Unison Research really have got the recipe right with this amplifier as it sounds sublime to me and I could sit here and probably type a hundred superlatives and you would probably read it in disbelief, so I am going to have to justify in words the sounds that I heard from this amplifier.

The interesting part of this review was pairing the Unison Research amplifier with different speakers, one of which was supplied with this amplifier and a Reloop turntable as the source, all from the same distributor as one of their recommended packages.  I won’t mention the Reloop turntable in this review as that will feature in a separate review with the Unison Research Triode 25 and Opera Mezzza speakers as a complete set.

I first coupled the Unison Research Triode 25 into my resident system and immediately it was apparent just how lucid and insightful this amplifier really is and surprisingly quiet and noise free too.  Trust me when I say it took no effort at all to listen to this amplifier producing real music, bursting with tonality and dynamism in a truly effortless way.  I have heard other EL34 amps produce this level of sound quality, but the Unison Research had that top level of polish and refinement that to date I have not heard elsewhere from EL34 valves.  Hard to describe, but the sound had a rich liquid silkiness which you might infer as being masked or veiled, but not so.  Leading edges were crisp and sharp enough to have a shave with, but not sharp or edgy either.  I’m struggling with the right words here (unusual for me) but would it suffice to say that I had no cause for complaint with anything I heard, with one small exception.

Bass was extremely clean and tight, perhaps a little too tight as that swift kick in the guts power a solid state amplifier can deliver with plenty of beefy watts behind it, the Triode 25 couldn’t quite muster.  I bet you valve fans are muttering under your breath at reading this, but you play something like Supertramp’s “Dreamer” or Dire Straits “Private Investigations” at full chat on a valve and then a solid state rig, then come back and argue!  This was no real surprise as I have yet to hear any valve amplifier compete with that, so living with a valve based power amplifier is all part of the whole package for me.  Conversely, there isn’t a solid state amplifier that could quite produce that sweet silkiness in the treble and midband the Unison Research Triode 25 possesses so I will settle for an even score here.  You pays your money and takes your choice, as they say.

Listening to Fink’s “Wheels Beneath My Feet” album recorded live at various venues revealed a depth of image and soundstaging that was all enveloping, extending beyond the speaker boundaries and depth-wise not lacking by any means.  My biggest bugbear with this album is Fink’s diction which makes following the lyrics rather difficult, nay impossible at times despite the songs inviting you to sing along (I use the word “sing” here with some caution).  The album’s true forte though is the instruments, with some stunning well recorded drum playing and bass guitar.    When the drummer hits the Floor Tom in the track “Sort Of Revolution” it should penetrate to the centre of your being with it’s power and slam, but as mentioned above the Unison Research amplifier just fell short of that idea.  In it’s defence though, the ambience of each venue shines clearly through and you can easily discern the size of the venue and it’s acoustics.  The cymbals sounded exactly like struck cymbals should sound like, full of vibrancy and energy so you were in no doubt at all that metal was being hit.  Track one on the album is called “Biscuits For Breakfast”, opening with some delicious  acoustic guitar and Ride Cymbal playing, recorded with great precision, joined soon afterwards by deep bass guitar plucks, all a joy to listen to.  Track two called “Perfect Darkness” again has some great intro drumming with snare drum rim knock and kick drum.  Of particular note was how real the audience sound was, seemingly surrounded by some very enthusiastic clapping and cheering.

Time to give the Unison Research amplifier a good workout now, with Porcupine Tree’s “Deadwing” album slotted into the CD player’s drawer.  This album is full of rawness in the recording and it easily wrong-foots many a system, but all credit to it, the Unison Research Triode 25 managed to tread that fine line between  accuracy, delicacy and smoothness, avoiding for the better part the raw edgy harshness that this album can output, yet not totally mask the album’s recording shortcomings.  To be truthful, this is the kind of presentation I enjoy for my personal listening; excitement and dynamics without being sonically assaulted by the drawbacks of absolute accuracy and fidelity. 

Next into the fray came a pair of Opera Mezza speakers.  On my resident system they had a weird ‘beaming’ effect whereby there was a glorious sweet spot dead centre and a metre either side of that, but beyond that boundary the sound collapsed severely, losing bass and treble definition in my listening room.  Paired with the Unison Research amplifier I didn’t notice that effect quite as much.  That pairing was fine tonally and dynamically, but not a big bold sound by any means which I would best describe as “intimate”, best enjoyed at lower levels, which sounds rather perfect for those who live in thin walled houses with complaining neighbours.

Out with the Opera speakers and in with a pair of Roksan K2 TR-5 S2 speakers, which have a superb ribbon tweeter and larger cabinet dimensions than the Opera speakers, so I was expecting a lot more bass.  Bass indeed now took a good leap forward and the ribbon tweeter coupled with the silkiness of the Unison Research amplifier was a great marriage.  However, the Roksan speakers have a quite prodigious bass output and the Unison Research couldn’t keep as tight a grip on the bass registers as I would have liked, resulting in a slight overhang  I am being picky here and if I didn’t have my resident system as the benchmark then I might not have been quite so critical in this respect.

Last but not least, a pair of Audiovector QR1s (Full review soon) were connected up to the Unison Research amplifier.  Again, this speaker has ribbon tweeters like the Roksan’s and sure enough treble output was as sweet and mellifluous in that respect as the Roksan speakers.   Bass had a less prodigious quantity and was all the better for that when paired with the Unison Research amplifier, providing a better balanced sound.  In fact, I purposely left the Audiovector speakers connected for quite some time.


If I were in the market for a valve amplifier then this would probably be the one I would buy.  I listened very hard for any fuzziness, harshness, noise, distortion, ringing, muffling, or veiling and I found none.  Sure, the bass lacked concussion inducing power but I could live with that, as what was there was clean with no trace of bloom or boom, which does annoy the heck out of me.  On the positive side it has a sweet beguiling sound that you can listen to for many hours and not once will it displease you in sound terms.

It is well specified, well built and easy to maintain too, especially the built-in bias adjustment settings.  Comes with a great remote control and that pleases me too.  I like the sturdy and thoughtfully designed chrome plated valve protection cage which keeps hot valves out of human harm’s way.

In summary then, if you hanker for a valve amplifier then this one HAS to be on your audition list for sure and I give it a high recommendation.


Build Quality:  Beautifully crafted in every respect and the design is a tribute in how to make a valve amplifier not look like an ordinary run of the mill valve amplifier

Sound Quality:  Sure footed and highly mellifluous, you owe it to yourself to audition or miss a sonic bargain

Value For Money:  As it stands head and shoulders above the herd in sound and build quality, it has to be good value for money

Pros:  Build, sound, ease of maintenance and a remote control.  You really are being spoiled with this one.

Cons:  None, except for a slight shortage of gut thumping bass power, to be expected though.

Price: £2600

Dominic Marsh


  • 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)
  • Power Consumption: 300 watt max
  • Fuses: T6.3A from 100V to 130V T3.15A from 220V to 250V
  • Dimensions: 30 cm x 45 cm x H. 20cm
  • Net weight : 20 Kg





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