Hi! I use my HD PRO with a Brunetti RockIt power amp and my experience is: do not stop your attempts in "power amp" output setting. I use "direct" output and cabinet simulator to have my best tones. Connections are important, of course, but, in my case, I'm "obliged" to use my power amp in bridge mode to "squeeze" more power from it, so I use mono unbalanced output (no XLR available on RockIt). However the settings' influences on tone are bigger and bigger respect connections' type. Ciao!