Stereo sound on center speaker in xmms with alsa
 

I have SoundBlaster live 5.1 with 5.1 creative system. Alsa is installed and I configured alsamixer so all my speakers work, but when I play mp3 (which is stereo) in xmms I hear sound in my center speaker. Is this a alsa or xmms bug? I'm using alsa output plugin in xmms.
Is there a way to fix this problem in alsamixer, but not by turning off the center speaker volume.