I’m really confused now. You have the songs on multitrack ADAT, or stereo DAT? If you have the multitracks, then you can get them transferred to individual tracks and remix them. Stereo will be very difficult if they have the poor mix and clicks?
the ADAT sounds hopeful, stereo less so. The only snag I can see is the rights? Did the musicians who are playing sign buyouts so you can market their performance? Pretty common on these deals, but when you release it, you’re expected to at least credit them as featured contributors.
do you want to learn the techniques and buy the equipment to do the remixing, or pay somebody else again?
ADAT transfers are still quite available. But the tapes are fragile and the machines all getting old.