Sound setup on ASUS m2n-e SLI board (CM6501)
Audio has got to be one of the most frustrating parts of setting up Linux. It looks like finally the situation is improving with most distributions adopting pulseaudio as a middle layer. Still, getting sound working on my cheap ASUS M2N-E board proved to be difficult and I wasted way too much time tinkering with it. Hopefully this post will save someone from my misery.
The root of the problem seems to be how ALSA handles the CM6501 (C-Media Electronics USB audio) chip. Try as I might, there seems to be no way to get sound out of the lime colored connector. According to the manual that is either "Line Out" or "Front Speaker Out". I began to make progress after running:
speaker-test -c 6
Aside from the lime connector being apparently dead, the channel mapping does not match the ASUS manual. In 4 channel mode:
| ALSA Channel | ALSA Name | Plug |
|---|---|---|
| 1/2 | Front | None |
| 3/4 | Rear | gray |
In 6 channel mode:
| ALSA Channel | ALSA Name | Plug |
|---|---|---|
| 1/2 | Front | None |
| 3/4 | Rear | orange |
| 5/6 | Center/LFE | gray |
The most straightforward way of getting some sound working is to configure pulseaudio with the following one line in /etc/pulseaudio/default.pa:
load-module module-alsa-sink device=hw:0 sink_name=front_stereo channels=4 channel_map=aux0,aux1,front-left,front-right
I see I'm not the only one having problems with the CM6501 and I guess Linux is not solely to blame. In retrospect, I should have bought a decent PCI sound card years ago. Anyone got recommendations?