Wow , I do the same thing cab-wise . I run a Mesa WD-800 into the stacked 2x10's . The Mesa's set to 2 ohm to knock it down to 600 watts. People are surprised at how much punch those little Ampegs cabs can put out. It must sound pretty sweet with the portaflex. I built a sturdy little (2.5' x 2.5') foot x 15" high box to stand the stack on. It got them up closer to ear level, off the floors and gave them an even better throw. (Filled the box with padding so it didn't add any boom). Nice little rig ..