Originally Posted by meynaf
But are they on the same power line input ?
Don't mechanical parts take 12V where paula uses 5V ?
And? PSU has single transformer with two outputs (or more - never found Amiga PSU's schematics) - usually highest voltage is used as feedback voltage - any changes in 12V are injected to 5V lines also...
Side to this Amiga audio path using both lines ( i.e. 5V, 12V also -12V is used) - Vcc (5V) is used to supply Paula (digital and analog part share same voltage pin), Vref is created in resistor divider from Vcc, there is separate analog ground, OPAMP are directly powered from +12/-12V lines - there is only few capacitors and resistors working together as very simplistic filters. This is not bad but definitely not the most optimal way - however it is justified for computer where cost of production was sensitive - just enough but not 14 or more bit - if you really wish to have HQ audio then all those problems need to be addressed properly, audio supply and ground need to be clean, proper PCB layout etc.