soundberry Unison Simply Two.Le Valvole!HiFi best buy Italia.

Integrated full valve operated amplifier Maximum output power: 12 watts RMS per channel Input impedance: 47 KOhm/100 pF Power valves: EL34 (one per channel) Working class: A Configuration: pentode Net weight: 16.5 Kg

"Excluding style with a finish that would do Ferrari proud, this little Italian glower is bellissimo with an antipasto price tag. [..] This is a carefully designed amplifier with much attention to detail. The speaker binding posts are solid and of the type you would expect on amplifiers costing at least twice as much. [..] The Simply Two can handle dynamics with extraordinary dexterity. [..] The Unison design is extremely musical and so compatible with a variety of styles."World verdict: Good circuit design and a highly musical performance make this a top quality amplifier.

Nothing is really new in electronics design, its said. But there are always new ways of executing old ideas. One of these is Unison Research`s S2K, in which the Italian brand`s designers have unusually used a KT88 output valve in single-ended mode.

Single-ended amplifiers, specifically single-ended triode valve amplifiers, have long been the preserve of hi-fi`s most radical enthusiasts. Over the last decade, depending on your point of view, they`ve either represented the only true path, or the ultimate in hi-fi lunacy. (If you want to go there, just visit soundpractice.com.) SET Value amplifiers are usually associated with horn loudspeakers, for the fairly good reason that only horn speakers are sensitive enough to give realistic dynamics when the power available is less than 10W. The conundrum here is that if the loudspeakers sensitivity is high enough to make the most of a puny power rating, it will also inevitably make the most of the amplifier`s background hum and noise. So although high sensitivity speakers (say 95dB/W-plus) can work well with only a few watts of power, they will also mercilessly reveal any shortcoming in the signal-to-noise department. Single-ended triode amplifiers also tend to have poor bass extension and weak control of he bass (poor damping factor) and usually a rolled-off treble as well.

Because the single ended output stage needs a special kind of output transformer which has to be custom built, SET amplifier tends to be very expensive. Many "enthusiast" valve amplifiers have been put together by small and rather umprofessional companies, and they`ve frequently tended to be badly made, unreliable and ugly.

However, Unison Research has outgunned and outlasted a host of less well-equipped, less professional valve amplifier makers to bring us, not exactly tubes for the masses, but definitely tubes for the sensible. Unison Research designs and makes its own output transformers, which is arguably half the battle, and makes amplifiers which dont hum or hiss.

The bigger selling Unison Research products have probably been its single-ended ultralinear designs, starting with the Simply Two stereo amplifier, which used one EL34 pentode valve per channel. This configuration just about got the power output into double figures. The follow up to the Simply Two, again with one EL34 per channel, and a rated output of around 12W a side, was the S2.

Then in one of those moves which seems obvious once its been done, Unison Research substituted KT88s for the EL34s, to produce the S2K. As the company points out, there was much more to this than just plugging in a different valve, and the S2 design has been completely reworked to produce this beefier, KT88-powered version.

Physically, the S2K is compact ( 275 x 410 x 165mm, whd) and easy to handle, though thanks to the necessarily massive output transformers, its quite heavy at 18kg. In fact, it really looks much the same as the S2 except that the slim and unassuming EL34 tubes have been given way to those bulbous and imposing KT88s, which have instantly made the amplifier look purposeful and quietly impressive. If you disapprove of hand-carved lumps of real wood attatched to electronics, you`ll probably shun Unison Research anyway. Its a matter of personal taste. Some of the company's wilder flights of lacquered fantasy have struck me as merely bizarre; but here, I think the effect achieved by stylist is pleasantly luxurious but not overdone.The two control knobs (volume and source select) are nicely machined from stainless steel, natching the heat-reflector plate which surrounds the valve bases. The two small tubes are ECC82 double triodes. No cover is provided, and the valves do get hot; a consideration if young children are around.

On the back are gold-plated phonos for the five line-level inputs (including tape) plus one pair of tape putputs. The volume control potentiometer itself is a selected ALPS component. Thanks to a motor drive arrangement, this can also be rotated to turn the volume up or down by the pressing the up or down buttons on a neat little wood-cased remote control handset. This remote send radio signals, not infa-red, so you dont have to point it at the amplifier and you can even control the volume from another room.

I listened to the S2K over a number of weeks and with many different system combinations, ranging from my trusty (sadly now obsolete) Rogers Studio 7 to Avantgarde Uno horn hybrids to original Quad electrostatics. Also, thanks to Stuart Shepherd, I was able to give them a brief workout on a pair of Lowther Audiovector horns. The S2Ks noise levels are so low that even 100dB/W-plus horn systems won`t catch it out. Other partnering equipment included Exposure and Musical Fidelity and Gamut CD players, and an SME Model 10-based analogue front end.

The S2K worked really well with the Avantgarde Unos, and this combination could bring the music to life quite breathtakingly. A good example of this was Wes Montgomerys Full House, a 1962 Riverside Recording (VIC)- 60171 in JVCs XRCD reissue series, with saxaphonist Johnny Griffin on probably best-ever form. Here you could really feel the drive and intensity of the groups uptempo performances, in a way that swept you along exhilaratingly.

If there's one word that describes the S2K, it's "beguiling". On clasical music, it was capable of displaying the tone colours of individual instruments in a quite effortless way, so that individual lines caught the ear sounding fresh and spontaneous, while conveying the space around the instruments well too.

With the Avantgarde speaker, of course, the built-in amplification in the active woofer boxes relieves the system aplifier of responsibility for the bass. However, trying the S2K with other, conventional, speakers soon proved that it was reasonably capable at the bottom end; rather light, yes, but certainly with more firmness and solidity than many simple valve amps can muster. Turning to the electrostatics (mine having been expertly restored by Andy King) was a delight, especially when using vinyl sources.

Its pretty debatable whether 15W or so is really enough for a conventional, low-sensitivity 30-litre box speaker like the Rogers Studio 7,but I tried them anyway, with good results at or below my usual listening levels (which are not particularly loud). Again, at moderate levels, the sound was smooth, controlled yet detailed and airy. On modern, easier-to-drive and higher sensitivity speakers (I tried a pair of bookshelf Missions with great success), it sounded more relaxed and sparkling.

My brief trial of the S2K to Stuarts Lowther speakers was illuminating for me,though perhaps not very relevant for most users.The amplifiers generally clear, well articulated midrange quality came over well, and on a demanding choral recording, for example, it could reveal the singers diction and the intricacy of the part writing with attractive clarity while conveying the ambience and spatial feel of a large recording venue.Stuarts speakers ( in hich one of the two Lowther units fires forward, adding to the mid and treble, but does not contribute to the bass) do need the bass boost which his Quad "tilt" control can provide, and which of course isnt available form the Unison or from other amps which lack tone controls. However the quality of the bass was fine:firm, controlled and tuneful.

Criticisms? Well, Im afraid I cant put my hand on my heart and say that the S2K does everything that a full-blown, zero-feedback single-ended triode amplifier can. Even with horn speakers, you dont really quite get that naked, shimmering plasma of reality, for which SET maniacs will sacrifice everything else (wives and families included probably). Despite all the air and detail, the S2K has a quality that I can best describe as "controlled", which is why, earlier, I called the amplifier "beguiling" rather than, perhaps, arresting; there is a certain dryness to the sound. On the other hand, unlike many a "zero feedback" monster, it produces almost literally no background noise, and there are no thumps, creaks or any other worrying noises. It is pretty revealing, and deserves careful choice of matching electronics, as well as speakers; those who choose this amplifier should certainly beware of CD players with any tendency to sound thin or hard.

Unison Research must be congratulated on the S2K, it really is a valve amplifier without foibles. The company is in business for the long term, and with confidence-inspiring products offering such exceptional value for money as this I'm sure will continue to go from strength to strength. If you have always hankered after a valve amplifier but feared the practicalities, you owe it to yourself to hear this one.