Recording JUST the left?

More gremlins during open mic night.

For some reason the USB was only recording the left channel, or atleast the right channel was VERY quiet.

No idea why this is, it was playing through iTunes, into the desk via headphone out then back into the Mac with USB fine. I had ProLevel up and could see both channels perfectly. Start recording and the right channel drops to pretty much silence.

Hopefully this will all be alleviated by the imminent arrival of our new Firewire desk. Meanwhile, any ideas?