Hi Matthew,
You asked about whether you could send VoiceOver's speech and the
system sounds through another sound card or through Bluetooth headsets.
Are you just trying to find a wireless solution that lets you work
without being tethered to your Mac? If so, here's a thread from
earlier this year about wireless Bluetooth headsets on the Mail
Archive pages:
http://www.mail-archive.com/discuss%40macvisionaries.com/msg28074.html
This is Greg Kearney's post about how, with a wireless bluetooth
keyboard and headphone setup, such as his wife uses with a Mac,
VoiceOver can also usefully be put to work by sighted users.
To read through the later posts in the archived thread with Safari,
just press Control-N to go to the next post in the thread. You'll
see Shaun's comment about how he uses a Logitech headset this way. If
you want to move back to the previous post in the archived thread,
use Control-P.
HTH
Cheers,
Esther