sound troubleshooting on Dell gx260 desktop

[tompoe at fngi.net]

I have GX260 Dell Desktop with external microphone and ubuntustudio 
installed.  No sound. 

I get login wav file playing when entering session, and from terminal 
can play wav files with aplay.  I futzed with the volume control panel, 
but now need to find steps from command line that would let me try to 
pin down where the sound pathway is being blocked.  Sounds are enabled 
under System ->Preferences, ESD is now disabled, but no luck.

Any help appreciated.
Tom