I LOVE my Peavey Basic 112, the Red-face version from 2004. I replaced the 8 ohm with a Mesa Powerhouse by Eminence 4 ohm and it's now a super clean sounding 70 watts! But concerning the feedback issue, are you paying attention to the idea of unity gain? I use a BDDI and favor the treble side, but if I try to crank the BDDI too far past unity then I get feedback when too close. Just a thought.
X8
