you could run a upnp server that streams whatever your computer is playing, and then listen to that stream on your phone.
very convoluted though. and there would be a lot of latency.
could also try shoutcast udp streaming, that should have lower latency.
is this motherboard audio? some motherboard audio chipsets have reconfigurable jacks, so if one is messed up, you may be able to use another & reconfigure it in software.