I am willing to put my head on the block and state that no hardware synth connected by usb or firewire for audio back to the host will be able to run more than one instance. The single instance has to think it owns the entire usb/firewire bus of the synth. We are controlling a single hardware box from inside a host, nothing more. If you want to run 20 instances of Vanguard in a host, its an entirely different setup to a single TI connected via usb.
I suggest you ignore my signature with this post
B