Unison s6_cherry Unison s6_rear


The latest version of the Unison Research S6 integrated amplifier is the result of over 25 years of experience with building valve amplifiers that have been praised all over the world for their beauty, reliability and performance. Our main goal with the S6 was to create an EL-34 integrated amplifier that has compact dimensions yet is able to drive most speakers comfortably – even those designs with relatively low efficiency. The S6 uses three EL-34 tubes in the output stage per channel, connected together in a triple-parallel configuration that operates in single-ended Class A ultralinear mode. With this design, the S6 is able to supply an ample 35 watts per channel. Both 4-ohm and 8-ohm speaker outputs are available so that you can match the loudspeaker of your choice to the S6 for the best results. The S6 was also designed with simplicity in mind. Our designs ensure that a minimum amount of components are found in the signal path, because we believe that the finest sound quality is the result of an unimpeded signal flow. This simplicity also translates to an amplifier that is more reliable and trouble-free in its operation.


Type: Stereo Integrated Valve Amplifier
Output Stage: single-ended parallel, ultraliner
Classe: pure A class
Output Power: 30/35 Watt/channel
Frequency Response: 20 – 50000 Hz
Output Impedance: 6 Ohm
Input Impedance: 47 kOhm
Inputs: 5 line
Outputs: 1 tape, loudspeakers
Power Consumption: 265VA max
Dimensioni : 35 cm x 21cm x 49 cm (L x H x P )
Net Weight: 55 lbs


Some folk believe that technical specifications tell the whole story. If you’re one of those people, then valve amplifiers are not for you.

In just about every area, from power output and distortion levels to energy consumption, such designs are so far behind transistor-based alternatives it’s easy to wonder why manufacturers still bother.

But then, listen to a valve design as good as Unison Research’s new S6 integrated amp, and it all makes sense.

It’s the S6’s speed that grabs our attention first. It tracks a signal with a impressive lack of inertia, which translates into a wondrous ability to render the nuances of Nina Simone’s voice on I Loves You Porgy with a delicacy we rarely come across.

Richness, power and tenderness: it’s all here, in generous portions. In the midrange and treble the S6 is the real deal. It’s agile and insightful, delivering the low-level details that define the texture of instruments and voices brilliantly. Not only that it keeps every musical strand in place even with demanding recordings such as Beethoven’s Fifth.

Here, the Unison Research manages decent dynamic swings and delivers them with a confidence barely reflected by the 33W per channel power rating.

Sweet but not squashy-sounding

Conventional wisdom has it that valve amplifiers sound smooth, warm and soft.

Good designs such as the S6 prove things don’t have to be that way.

Yes, it has a sweet presentation and a lack of hardness that few transistor alternatives can rival, but for all that niceness there’s enough transparency for it to sound appropriately brittle with harsh recordings such as The Magnetic Field’s I Don’t Know What to Say.

Hi-fi aspects such as tonal neutrality aren’t ignored, either. The S6 even times decently, though if this aspect of performance is paramount we would point you to the Lavardins and Pliniuses of this world.

The valve stereotype the Unison Research does live up to is the ability to deliver sound in an organic manner.

Dynamic shifts are rendered in a lovely fluid manner, so changes in intensity sound wholly natural with voices or instruments. Most transistor-based rivals sound just a little mechanical and stilted in comparison.

It’s as though they handle subtle level changes in distinct steps, while the S6 varies things on a continuous scale. Once heard, this ability is hard to do without.

A spellbinding sound

So good is the S6 in its areas of strength that we find it easy to forgive the lack of outright attack.

Rivals that can better it in this aspect don’t even come close in other areas. It offers a viable alternative to the established class leaders – one where the sonic character is so different from the norm that we can’t imagine a person being undecided in a head-to-head comparison.

So, then, if you fancy something out of the ordinary, and can take the care necessary to build a compatible system of suitable quality, this Unison Research amplifier is a simply terrific buy.