tipo você tentou desabilitar o som onboard ?
o que retorna os comandos abaixo .
cat /proc/asound/cards
lspci | grep Multi
No meu caso tenho uma SB Live que funciona , mesmo com a onboard habilitada ,mas para ter um funcionamento perfeito eu desabilitei a onboard.
edson@Zumbi:~$ cat /proc/asound/cards
0 [Live ]: EMU10K1 - SB Live [Unknown]
SB Live [Unknown] (rev.10, serial:0x80651102) at 0xdc00, irq 19
edson@Zumbi:~$ lspci | grep Multi
0000:00:0b.0 Multimedia audio controller: Creative Labs SB Live! EMU10k1 (rev 0a)
Meu lsmod
edson@Zumbi:~$ lsmod | grep snd
snd_emu10k1_synth 7520 0
snd_emux_synth 36032 1 snd_emu10k1_synth
snd_seq_virmidi 7168 1 snd_emux_synth
snd_seq_midi_emul 7584 1 snd_emux_synth
snd_seq_dummy 3620 0
snd_seq_oss 33600 0
snd_seq_midi 9088 0
snd_seq_midi_event 6848 3 snd_seq_virmidi,snd_seq_oss,snd_seq_midi
snd_seq 50736 9 snd_emux_synth,snd_seq_virmidi,snd_seq_midi_emul ,snd_seq_dummy,snd_seq_oss,snd_seq_midi,snd_seq_midi_event
snd_emu10k1 118340 3 snd_emu10k1_synth
snd_rawmidi 24704 3 snd_seq_virmidi,snd_seq_midi,snd_emu10k1
snd_seq_device 8460 8 snd_emu10k1_synth,snd_emux_synth,snd_seq_dummy,s nd_seq_oss,snd_seq_midi,snd_seq,snd_emu10k1,snd_rawmidi
snd_ac97_codec 83452 1 snd_emu10k1
snd_pcm_oss 52704 1
snd_mixer_oss 19296 1 snd_pcm_oss
snd_pcm 88840 3 snd_emu10k1,snd_ac97_codec,snd_pcm_oss
snd_timer 24164 3 snd_seq,snd_emu10k1,snd_pcm
snd_page_alloc 10600 2 snd_emu10k1,snd_pcm
snd_util_mem 4448 2 snd_emux_synth,snd_emu10k1
snd_hwdep 8896 2 snd_emux_synth,snd_emu10k1
snd 54884 15 snd_emux_synth,snd_seq_virmidi,snd_seq_oss,snd_ seq,snd_emu10k1,snd_rawmidi,snd_seq_device,snd_ac97_codec,snd_pcm_oss,snd_mixer_ oss,snd_pcm,snd_timer,snd_hwdep
soundcore 9600 2 snd