I am running into a similar issue. I dial in a good tone and then when I get to practice I have to crank my power amp and the master on the HD Pro X to get to a level we can hear above our drummer. Then, I start getting feedback becuase I have had to crank the levels (simulated amp volume, Master POD volume, and power amp) up so high. As a result I have to get really aggressive on my noise gates, which is kind of a buzz kill to the tone and the sustain. I was hoping that when I moved to the Matrix power amp I would be able to leave the Pod's volumes in a sweet spot and get the volume needed from the power amp. Not quite happening so far.
My Setup:
HD Pro X Unbalanced Left and Right Outputs (Set to Line) => Matrix GT800FX => Mesa 4x12 Cab
Any suggestions?