mono to stereo input in ALSA

[Ken Schutte <kschutte@xxxxxxxxxxxxx>]

Hi,

When I play a mono source into line-in, is there a way to have ALSA map 
this to left and right channels, so that it's as if I had a stereo 
input?  With a guitar input and wearing headphones, it's pretty annoying 
to hear only on the left.

Thanks.