I flound olut the hard way that I cannot install my M-Audio DuoSport or the M-Audio UnoSport MIDI USB devices at the same time as my E-MU 1616M.
Turns out they share some critical files down deep in the system somewhere and you can't have both installed at the same time. Result for me was that I could use neither. Even when only one of the two devices was actually connected and running. The driver software for the E-MU is where I place the blame.
I think E-MU has problems with their drivers on their products.
Wonderful sounding soundcard, difficult to keep it up and running...
--Mac