I'm looking at making something work for the PA1002, and have some questions. First, does anyone know what sort of solid state relay connection is used internally? Does it open the signal path, or short it to ground, or do both? They refer to grounding the signal in the service manual circuit description, but since it has DC on both IN and OUT terminals, I think they must also switch the signal path open. Anyone know? I'm leaning toward only grounding the audio signal to mute, which requires a little different strategy. I'm not a fan a sending signals through CMOS switches if it can be avoided. Point is, I prefer to try and make the replacement sound better than stock, not the same. Also it should allow op-amp swaps. Looks like standard single or dual op-amps will work fine here. For the mute switches, I'm looking at Form A SS switches with lowest ON R. They need resistance in front to work as a mute though, so will likely be moved to another area. Any thoughts or comments from people that have already tried this are welcome.