Sound card as MOH source

Hi people

I’m having trouble getting a Sound Blaster 5.1 working as the source for music on hold. It seems like the card refuses to do one channel recording which Asterisk requires.

Using only one channel I get this result:
root@matt:/var/spool/asterisk/soundcards# /usr/bin/arecord -q -c 1 -r 8000 --buffer-size=2048 -f S16_LE -D hw:1,0 -t raw
arecord: set_params:905: Channels count non available

Using two channels allows me to record however it doed not appear asterisk will accept this.
root@matt:/var/spool/asterisk/soundcards# /usr/bin/arecord -q -c 2 -r 8000 --buffer-size=2048 -f S16_LE -D hw:1,0 -t raw

Does anybody know a way to record only one channels with a Sound Blaster 5.1 or get asterisk to accept a two channel recording?