So I have the 6505+ Head, and its great.
Was wondering if anyone knows what the Pre-amp output is used for?
Is it Unbalanced or is it balanced?
Is it used to send another signal to ANOTHER head?
Generally used to feed another amp when you need more power. For example, playing a large stage with four full stacks, you'd need the 5150 to power one stack, and then another set of amps to power the other stacks.