USB sound

[R Kimber]

Hi:

I've been having problems with UBS sound for some time (it used to work
about 6 months ago). I find that any USB sound device that I connect is not
recognised, and is not listed by aplay -l

I've googled for this and found links to a number of unresolved bug reports,
so my question is: does anyone currently have USB sound working with an
external sound device (e.g. a DAC or a streamer)? 

I'm using 12.04 LTS

Thanks.
-- 
Richard Kimber