Any finding at all will help, of course
Well the volume knob is click-less like the aperture/iris ring on a cinema lens. Volume level is directly shown on the screen and therefore there's no stop when you've reached infinity. This design is a bit idiosyncratic.
Of course the knob magically rotates when you use the remote : ) Always loved this feature.
The gap on the top is see-through. I can foresee serious problems with dusty environment. I don't know why Sony chose to have the amplifier to be so open. Their S-Master HX is pretty energy efficient. That being said, there's still a Class-A amp circuit inside working as error correction to the Class-D amp, maybe that one can get hot. After running the ZH1ES for a while the top plate is a little warm. Very hard to tell since the chassis metal feels like leather... could be just the tactile feedback tricking my brain.
Buttons don't feel nice. Well... it is Sony that we're talking about and I feel like this is the same button mechanism they used for their Alpha cameras... plasticky and hard to tap.
The menu is huge. You can adjust DSEE HX, DSD Remaster Engine, DC Phase Linearizer and various pre-out, L/R balance settings and such.
And you'll need to download Sony's driver for Windows. Otherwise an easy setup.
Overall this thing looks gorgeous. The build quality is impeccable. The weight is very substantial and my only complaint would be the lackluster button tactility.
Did I mention the metal feels like leather? Very nice finish.
I'll need some more time with the amplifier to talk about the sound since... amp improvements are very subtle.
But it's quite noticeable that a balanced Z1R is on a different level from the single ended unbalanced Z1R. Bass is more detailed, this is probably part Z1R and part ZH1ES.
Don't have any other summit-fi headphone lying around so it'd be tricky to test out the pairings...