I have been using a Mac Pro (Snow Leopard) with an old Multiface and the original driver.  A couple of years ago I bought a Fireface 800 that I have been using on the same machine.  At that time, I installed Totalmix.  I could sometimes use the Fireface with no problems but sometimes the computer would lock up and didn't want to shut down.  Also, the basic function also seemed to get way less reliable.  Is this likely a conflict of the two drivers?   Can I use both devices on the same computer if I just use one at a time? Can Totalmix be used with both the Multiface and the Fireface 800?