USB sound card

Is there a way to make MOC recognize my USB SBLive! external sound card ?

This is the job of alsa to recognize your soundcard.
Did you properly configure alsa and moc to use it?

@+

have no idea. i'm still new to linux, so i don't really know how to see. i use decibel-audio-player now, recognizes it, but i think it's pulseaudio, not alsa.

~/.moc/config:
# ALSA output device.
AlsaDevice = "hw:1,0"

makes mocp send output to my external usb card. The number might vary depending on your configuration, and you might want to use plughw instead of hw depending on the capabilities of your soundcard.