I did a recap on am LC III not too long ago and the SCSI died. Turned out to be too much solder on the pad on the cap near the SCSI Port and it was shorting out with another pad that was under it. Desolderig and resoldering the cap with much less solder fixed it.

I'm sure that you have the same problem in or around the audio circuit, though there are several caps there. Unsolder each one, inspect the pads and put them back in with a tiny amount of solder. It should fix it up.