A nine track drive would certainly not work with an ACARD adapter- they are "intelligent" designed for mass storage. And on top of that the only adapters I know of go the wrong way (IDE devices on a SCSI bus), though I haven't researched the reverse.
Derp yea. Forgot about that. I've only used the ACARD boards in music hardware not stand alone computers and forgot the direction.
I gave Josh Dersch a Xircom USB to SCSI not so long ago and we had no issue getting it to talk to an HP SCSI 9-track tape drive and even streaming music off of it. Linux handles both devices fine- plug and play. I have a Microtech USB to SCSI and it worked similarly although my 9-track streamer is sort of screwed. There's not even a project here. Connect the cables and try it, or forever hold your postulation... ;)
Cool. The USB to SCSI dongles I have are old and unbranded but NetBSD picked them up. Back then I think I was trying to use an embedded board, so many more options now. I had Pentium1 board with PC/104 sound card.
TBH, I think QIC tapes might be a bit better since you can mount the drive in the dash. There are 13GB versions or something so you could get a few blu-ray rips on each tape.
-- Ethan O'Toole