I've done quite a bit of listening to the modwright 9100es over the past 3-4 days and I feel that it is truly a high-end source.
It throws a huge soundstage with extremely good channel separation. It presents stage in an articulate manner placing every piece of the music in it's own concise spot in space. I'm looking forward to comparing that aspect in particular against the apl 3910 in the speaker rig.
One of the concerns I had before getting it was speed and pacing, tube outputs (especially poorly designed ones) have a tendency to slow things down just enough to to throw the pacing off a bit. I'm happy to report that is not the case with the modwright 9100es it keeps the O2's speed intact and has spot on pacing.
I do think one of it's biggest strength's is bass reproduction. It might be the bass reproduction I've heard it goes deep and can really slam when needed. But it can also be delicate in the way it lets all the nuances and textures of the bass notes through.
I'm sure the excellent bass ties in with this, but the player also has killer dynamics it transitions between quiet and loud passages perfectly never sounding too soft in the quiet parts or too harsh on loud ones.
That's about all the thoughts I feel like putting down for now, more to come soon.