Fedora 20 is no longer supported.
Qubes R2 is no longer supported.
Generally, I doubt anyone on the list will recommend you continue using such older unmaintained security software.
So..if your hardware supports Qubes R4.0, my suggestion would be installing that, assigning one of your PCI USB controllers to the Window HVM, and then utilize a hardware USB audio device for audio out of the Windows HVM.
B