We tested a very limited set of USB audio capable devices.

Behringer UCA 222 and UCA 202 has been tested successfully.

Those are one of the cheapest USB audio device available for about 30€.

Funkier USB audio devices like ones that have multiple in/out and fancy onboard features might not be fully supported.

USB audio support is pretty crude for the time being. AHI isn't really suitable for handling high end audio card that has for example 8 inputs/outputs.

Recording from external sound card hasn't been extensively tested either and already been reported to fail in some cases.