Thread Subject: Recording sound with USB Sound Card

I need to be able to record sound through a USB sound card
using 24 bit sampling. I have a Creative Audigy 2 NX,
Windows Vista Business, and Matlab2007b.

For a simple test I'm just looping from the "Front" to the
"Line In" on the USB sound card with a 1/8" cable. As a
test tone, I've used just a 1000 Hz tone generated in
Matlab. To play/record I'm using the
audioplayer/audiorecorder functions. When playing back the
recorded tone it is extremely distorted with no resemblance
to the original 1 KHz tone.

I have no idea why the act of looping through the external
sound card causes this distortion, I would greatly
appreciate it if anyone has any ideas they could share.