I’ve moved on to the official Raspbian release. This OS image using the hardware floating-point capabilities on board the RasPi and is noticeably faster than the Debian “squeeze” image was. It allows me to reboot when I’m powering the RasPi from my USB hub, something I couldn’t do before.
I’ve also tested a total of five different sound devices with Raspbian and ALSA for recording a mono microphone input. I’ve gotten one recording by fluke on a “Virtual 7.1 Ch Sound” device, and consistently get the claim that there is no capture device associated with the Behringer UCA202. The only device that has worked consistently for recording is a Syba “USB Stereo Sound Adapter” CMedia CM119. I didn’t pay more than $9 for any of the non-Behringer devices.
The CMedia is recognized, the controls come up appropriately in alsamixer, and arecord works without complaint on it. My only problem in simply going with this adapter is that I cannot reliably reboot my RasPi with it plugged into the USB hub. If it is plugged in on boot, the network interface throws “kevent 4″ errors. If the network is not plugged in, but the CMedia device is, ALSA throws a lot of errors at boot. Given that I want to deploy my RasPi remotely for a couple of weeks at a time, this sort of behavior doesn’t give me confidence. Things have improved since the earliest firmware I was using, but there seems to be a ways to go.
Syba SD-CM-UAUD USB Stereo Audio Adapter, C-Media Chipset, RoHS ($8.08 from Amazon)
The currently non-recording adapters:
Virtual 5.1-surround USB 2.0 External Sound Card ($1.78 from Amazon)
7.1 Channel USB External Sound Card Audio Adapter ($2.38 from Amazon)
Behringer UCA202 ($29.99 from Amazon)
Intermittently working adapter (I can’t say exactly how I managed to get one recording done with this):
Syba USB2.0 7.1CH Sound Adapter Add Stereo Output Mono Input Led ($3.28 from Amazon)