if you plan on using external amp for audio via the "headphone jack" you can completely omit the +12 too.
Interesting.  So you could just use a 5V P/S.  Which brings me to my original question.  How many amps are needed.  I looked at the manual but that doesn't mention minimum req. for power.
PS.  I always use an external amp, but a real small one, just the circuit board type.  Only because I find it very easy to adjust the volume with a pot rather than going through the menu