Crappy sound with Intel HD Audio codec
I have an ASUS P5LD2 motherboard with a Realtek-based audio codec. When I installed Fedora Core 4, it detected this codec and used the snd-hda-intel module to manage it. With the sound test, audio is clear.
However, if I play some Ogg Vorbis file in Rythmbox, I get crappy sound. I can hear the music, but there is always an annoying background noise. To isolate the problem, I tried to play the same file with ogg123: crappy sound. Then I tried to play WAV files with aplay: crappy sound!
In conclusion, everything that enters ALSA devices produce crappy sound.
I tried to set the controls in alsamixer without any result: I lowered the volumes, disabled Front mic, muted IEC958, without any result. I then tried to shut down esd (killall esd), and used esd -r 48000. This results in a crappy beep. I tried many other frequencies: 92000, 96000, 192000, always crappy sound. Everything I try results in crappy sound. I searched on this forum, found some clues, but nothing worked.
The ASUS CD contains a Linux driver, but it seems not to be for Realtek-based Intel audio, and it seems to be already included in recent versions of ALSA. I am using 2.6.14 SMP kernel.
Is there a way to get this Intel audio codec with ALSA? What can I do to get sound in Linux if the codec does not work?