I am totally happy with my Athem played through my Ultrasound amp.

When I play out, on, say, a generic rock and roll PA at a bar, are there any guidelines for 1/4" jack vs. balanced three pin?
Since Anthem is part USP and half microphone, should I play through my Baggs pre-amp? If so, should I then go three pin to the board, 1/4", or does it matter??