@Pilatomic: thnx! This sounds really helpful. One question. Is it correct that the +/-35v at the C5 capacitor is always available? So also when the BeoLab 6000 is in stand-by/Red LED on?
The voltage across C35 will only be present when the LB6000 is turned on. ( Relay RL1 closed )
If you need a permanent voltage, you can find it across C31. It will probably have quite a lot of ripple, but the DC/DC converter should be able to deliver a stable output voltage nonetheless.