I have a Multimedia audio controller ATI IXP SB400 and am running 2.6.18.8-0.5-default with openSuSE 10.2.

I do only get mono sound and /proc/asound/card0/codec97#0 shows:

0-0/0: Realtek ALC655 rev 0

PCI Subsys Vendor: 0x174b
PCI Subsys Device: 0x5215

Revision : 0x00
Compat. Class : 0x00
Subsys. Vendor ID: 0xffff
Subsys. ID : 0xffff

Capabilities :
DAC resolution : 16-bit
ADC resolution : 16-bit
3D enhancement : No 3D Stereo Enhancement

Current setup
Mic gain : +20dB [+20dB]
POP path : pre 3D
Sim. stereo : off
3D enhancement : off
Loudness : off
Mono output : MIX
Mic select : Mic1
ADC/DAC loopback : off
Extended ID : codec=0 rev=2 LDAC SDAC CDAC DSA=0 SPDIF
Extended status : SPCV LDAC SDAC CDAC SPDIF=10/11
SPDIF Control : Consumer PCM Category=0x2 Generation=1 Rate=48kHz

Is there anyone who knows to put it into stereo mode?

It should support 2, 4 and 6 channels output.