I don't really know how to solve your problem, but just some ideas.
Can you get digital audio? Some tv cards also show up as digital audio capture device, and you may be able to route that directly to your speakers without having to run a physical cable. I'm not sure how, but try poking around in /proc/asound
I have a similar problem on a similar chipset, explained
here. My TV card wants me to connect it to the microphone, but the back one won't work and the front mic works, but I can't get it to play directly to the speakers.
Currently my workaround is to run "sox -p -r 32000 -v 0.5 -w -t ossdsp /dev/dsp1 -t ossdsp /dev/dsp", where /dev/dsp1 is my TV card's audio capture and /dev/dsp the OSS mixer. It produces a 0.5 second lag in the audio, which is very annoying.