Re: Enable audio through HDMI on GT240
andrewju, from your description, it sounds like MPlayer simply gives up and doesn't output any sound if the HW doesn't support the sample rate of the audio in the file. Perhaps somebody more familiar with MPlayer's internals can confirm/deny this behaviour.
Your TV doesn't support 22050/32000 directly, which is relevant, because digital audio is being sent directly to it with your new card. I think with your 8600, you were using the analog output from your sound-card and looping that into the 8600 using a cable? In that case, the sound card may have supported those other sample rates, which the 8600 then digitized at one of the TV's supported sample rates?