I'm interested to see what everyone is recommending for an amp Senn 800. SS only please.
Currently have Eximus DP1
Normally I'd ask what your budget is, but seeing that the Eximus DP1 is ~$3K (USD), I'm guessing you don't care about cost too much.
The best solid-state amps that I've personally heard with the HD800 have been the Luxman P-1u and HeadAmp GS-X, each for different reasons. I wrote a review of the P-1u in this thread, as did several others: http://www.head-fi.org/t/466147/luxman-p1u-loaner-program-and-reviews
The GS-X contrasts from the P-1u with its cleaner, clearer sound which reinforces the HD800's treble, clarity, and soundstage openness - i.e., it can make it seem more holographic. It adds nothing of note to the mid-range or bass though, so if you'd prefer that you may want to consider the P-1u.