Shopped photos tell all?
Like the next shot, the Assistent 50 + Druid V combo played it rich, chunky and, in old 35mm terms, fully developed. Rather than lily white, the speaker skins are really a fat bone/ivory hue. In fact, that aspect would stand in nicely for the Assistent's treble: fully visible but weighty.

In this paler rendition—overbleached for emphasis but pointing at the transistor gestalt—the foliage of the indoor trees is far better separated. So are the album covers on the iMac. The seam on the red leather seat and the separate whizzer cones in the widebanders aren't even addressed by the upper color balance and white value. On raw transparency, we might argue that the second image wins. By the same token, there's no argument that the upper one is far more dramatic. By contrast, the second's colors are washed out. The tones inside the carpet's window reflections have disappeared altogether whereas in the first photo, they remain clearly visible. The point/s should be clear. What the Audio Valve integrated brought to the party was the same aesthetic as the first photograph. Your personal ideal might be somewhere in the middle. In our digs, substituting the Druid with the Accuton-driver Aptica accomplished that. With that ascertained, I was simply on a different kick.

To close out this visual exercise, the deeper black values of the first shot parallel the tubes' fleshy and extended bass which made for a very anchored 'foundational' presentation. This might seem counterintuitive for such petite output glass but was a fact all the same.

Readers who maintain a constant sonic tally based on what they already read now easily predict dynamic behaviour. And just so, the Assistent 50 was more focused on the macro end than the quasi subcutaneous little tremours of the micro scale. This smaller microdynamic resolution thus slightly delayed coming on song. To really 'show up' meant room not whisper levels. Here the higher S/N ratio of the transistor amps had the advantage. Likewise for superior phase linearity that didn't contend with coupling capacitors and output transformers. These elements flow into the traditional understanding of resolution. According to the pixel-count definition, the Mosfets had more. If your expectations for the sonic recreation of a recorded event rate believable tonal saturation and image density just as highly, they become other aspects of resolution; equally important elements that also want to be resolved. Now the twin tetrodes had the lead. This juggling act of dissimilar virtues flew much higher than the earlier speaker comparisons. Those were different in the same ways but far less so. Viewed from here, Audio Valve's use of tubes was far from faint. These tube qualities were potent and unmistakable even if aspects like image density and solidity were shared with our class A Pass Labs XA30.8.

A decisive circuit advance must be Helmut Becker's precision bias system. With practically eight power tubes per side, tight matching between them is vital for half-wave equality. This had to be key to the amp's excellent focus. Images locked tightly without drift, wavering or ballooning. Whilst they weren't backlit with emphasized venue data where the transistors had the edge, they were just as steady and specific. They simply felt bigger because their colour temperature was punched up. Coupled to Zu's expressive widebander which excels at the same qualities, this combination really spun the colour wheel. Big dense sound with rich tone, ready dynamics and powerful bass... it's not what 50 watts from pinky-finger tubes might promise but it's exactly what these delivered. It made even lean, sharp, pale or nervy recordings agreeable. Add utterly fuss-free operation and 20-year circuit maturity. Despite its slightly loud looks, the Audio Valve Assistent 50 struck me as really an ultra-conservative recommendation like blue-chip stock. That's short hand for utterly without risk. And a sure thing in hifi is a very fine thing indeed. With this my first-ever Audio Valve assignment, I felt I'd rather made a discovery...

Audio Valve website
UK importer's website