A few items I have tested and confirmed working (in no particular order):
Korg nanoKontrol2
Soulsby Synthesizers miniAtmegatron , this means..
Arduino MIDI/MOCO for LUFA (Arduni Uno MIDI hack)
Keith McMillen QuNeo
AKAI LPK25
iCON Cube Mi-3 (USB-Midi interface)
Waldorf Streichfett
Arturia Beatstep Pro (notable ground loop in my config, even with the supplied groundloop adaptor, did not try Axo DC power)
Novation LaunchpadPro
Elektron Analog Four
Dave Smith Intruments Tetra
Waldorf Blofeld Keyboard
Arturia MicroBrute