Unison Research Preludio review

We've seen quite a few products from Unison over the years and the family likeness is not hard to find.

That classic Italian love of medium-dark hardwood, for a start, and the proud way in which the valves stand alone. Like many other Unison Research products, this is a single-ended amplifier, using just one valve for the output stage of each channel.

Low power

Most amplifiers, both valve and solid-state, use push-pull pairs of output devices for reasons of efficiency, but single-ended operation has always had its advocates who cite its very simplicity as a major reason why it will (when done well) always sound better than push-pull.

There's a lot more to amplifier design than the output configuration, of course. But with its use of a single KT88 in ultralinear configuration, this amp does make a very interesting comparison with some rivals that use the same valve and the same basic configuration in push-pull.

The downside is output power - the rating being only around 14 watts - but based on years of experience, we've no hesitation in saying that suitably partnered, 14 watts can make for a very satisfying system that will play loud with no special pleading required.

Solid build

There's an intriguing blend of old and new in this amp, single-ended being the earliest amplifier configuration, while the KT88 is a relatively modern valve and the internal assembly uses a very modern circuit board and integrated circuit regulators for parts of the power supply, plus surface-mounted components in the remote control receiver section.

There's even an op-amp in there, though as far as we could see it's simply buffering the subwoofer output signal.

Build quality is very good and yes, the wood is solid and luxurious, too.

Surprisingly striking sound

If the Ayon is more an amp for lovers of melody than of rhythm, this is in many ways its antithesis. Belying any expectation one might have born of power ratings, physical size or mode of operation, the sound seemed to our listeners to be outstandingly rhythmic and lively, with excellent articulation and a very good sense of being there.

There are limitations, mostly in respect of detail and large-scale dynamics. Rhythm is largely about small-scale dynamics, of course, but over spans of seconds to minutes this amp seems a little less assured and can develop a trace of hardness in loud passages that seems to restrict dynamics a little.

There are some slight deviations from tonal accuracy, most notably a lack of really low bass. Heard in isolation this might indeed pass muster, but in the company of a bunch of its peers, mostly well-endowed in that region, the Preludio comes across as a shade light.

Strong imaging

Detail is good, especially in quiet passages of music, while imaging has excellent depth and pretty good lateral extension and definition. Despite some specific deviations from most people's idea of 'valve sound', this amp perhaps comes closest to embodying the valve ideal of musical involvement above all else.

If hi-fi specifics mean a lot to you, you may yet do better elsewhere, but this is undoubtedly a very musical amp.