how well does the relay volume control work?
the units look much better than expected, tho the side thing still looks wired
They really look better in "person" or live, especially the front. The rest ist indeed not final yet.
The relais volume doesn't give away a noise when moved/operated. While listening you get a tiny artefact after bigger steps but it's wholly different than the V281, so all those who still get startled by the V281 relais can rejoice. I personally never cared for it after the initial surprise how a relais volume can sound.
Much more important however is how it improves upon the V281 and this amp is a definitive upgrade. Some will probably be very happy to hear that the treble improved. Talking to you
@Justin_Time. What users of beastly tube amps called a slight hardness in the treble is gone with the US4. It didn't bother me on the V281 because a HD800SD brings the real treble flavor some might run away from in panic and thus I learned to choose my music more carefully and go to another headphone for pop and modern stuff. Still, the treble is more natural and neither subdued or rolled off, artificially warm or anything. It's simply more refined which for instance is easy to hear on rimshots and cymbals.
Also: the US4 has more low end heft, thump, grunt, kick in general with a grip on the driver control like Sauron on his mace. There is no artificial boosting or "sounding" here either. Man, did those LCD-3s sing with that amp. Other headphones used during the comparison: HD 800, Kennerton ODIN, Meze Empyrean.
For more detailed impressions I'd need to listen to them somewhere quieter of course. For now I'm kinda jealous though.