I *think* kenwood do similar bus adaptors for their systems too: Alpine definitely do.
Kenwood do offer an adaptor, for any of the later CD changer capable units, but it's a bit primitive. Alpine, as you say, also offer one, but you *have to* use it with an Ai-Net source unit, and without getting into modifying stuff, you also need a CD changer in-line. Pioneer also do one for the P series units, but they're all but impossible to get hold of in the UK right now, hence the fact we couldn't offer Steve the Pioneer option we originally suggested.
Who has stolen Steve's sony-stalk controller and almost has it wired to the empeg's serial port...
Wondered how long it'd be before someone tried that one :-)
Dominic
Cambridge Car Audio
http://www.cambscaraudio.co.uk