When might an AC (not DC) voltage be used as a power source for an audio device - most every guitar pedal I've ever owned converted line voltage - 120VAC to some lower DC voltage - often 9v or 12v DC. However, my Line 6 guitar processor (POD XT) uses 9VAC to operate - I believe that it is not being converted to DC before powering the circuit - what advantage does designing a circuit to be powered by AC provide? I found one answer here:
http://forum.arduino.cc/index.php?topic=186059.0 "Audio mixers often use AC because they need to resolve positive and negative voltage with respect to the audio reference / ground."
Still not clear - Thanks