soundproof: Yes. It's simple to work around not having MUTE, but also quite nice to be able to quickly dampen the sound when desired. I'll give it a look.
I had a dead mute channel on my Beomaster 5000 when I bought it. Some rapid flicking of the mute circuit on and off cured it, and it's been fine ever since. Have you tried doing this? No guarantees that it will work of course, but it seemed to do the trick on mine without any other interventions.
President, Beomaster 8000 Appreciation Society