The USB maintenance port is purely for comms with the ID40/41 card.

Best

Alex

HT/Main: 861v8, 808.3, HD621, 2 x DSP5200SE, DSP5200SEVC, 2 x DSP5200, Sony BD.
Lounge: 808.3, 2 x M33, Sony BD.
Office: Prime HA, Prime PS, Mac mini, Sennheiser HD25.
Odds & Sods: 568.2MM, 588, 562V, DSP5500HC, Explorer, DVP1080HD.