I went out and bought a USB sound card thinking that I'd be able to
use it on the Mobilepro 880.

I got a Turtle Beach Audio Advantage Micro. It's a pretty cool
adapter. I plugged it into my NetBSD/amd64 machine and it worked right
away. Sounded great.

So I recompiled the kernel for the Mobilepro 880 to include USB audio.
Unfortunately, this machine is WAY too slow to do this. It would play
about a tenth of a second of audio every half second or so. This was
using mpg123.

So if you get a bright idea to try USB audio on a Mobilepro 880, you
might want to think twice...

Here's what it looks like though:

uaudio0 at uhub0 port 1 configuration 1 interface 0: C-Media INC. USB
Audio, rev 1.10/0.10, addr 2
uaudio0: audio rev 1.00
audio1 at uaudio0: full duplex, independent

Andy