I've another amp that just died on me. the LCDs and everything still works, indicating the transformer's ok, but there's no sound output. As the amp is quite old, 10 yrs+, I suspect the EC caps are leaking. What other possible problems could happen to old amps?
No matter wether the amp is old or not, a fuse or fuses on the output or the output transistors could have blown, or the drivers could have also blown. Also, if the rectifier in the power supply for the amplifier stage itself is bad, that would do it, and if the power supply for the LCDs and stuff is still good, they would still work. Check all the fuses. Sometimes there's problems with relay circuits too. In old amps, sometimes transistors lose gain. And of course, electrolytics don't last forever either.
Anyway, I'm not much of a repair man, this is about all I can think of. Lots of things could go wrong in an amp.