Angstrom built 20090612 on RevC2 only left audio channel

HI everyone, I have just got a BB revC2 and able to install Angstrom.
But the problem is volume of the right audio channel is very small, left is fine.
I tried to increase every slider in the mixer window but no work.

Did anyone face this problem before? this is driver or hardware problem?

BTW I has a no name USB to Ethernet controller, its VID is 0FE6 and PID is 8101, when i plugged it in to a self-powered USB hub (Belkin hi-speed 4 port)
Angstrom detect it but failed while sending discovery.
I have tried to change the router (use buffalo one with DD-WRT firmware), shortening the cable, but still no work.
Does anyone have this controller and get it work?