I'm having a hard time believing this....
I recently ran my Mark IV side by side against a 5150...both through the same cab, rig, guitars, etc.
The 5150 was pure mud....saturated to hell, and very "Brutalz", but it was all buzz and no definition. Everything was enveloped in that over-saturated buzz. At first, it was pretty cool, as it was something I hadn't heard in a long time.
20 minutes later, right after rocking the 5150, I plugged the Mark IV back it....instantly, I got all the aggression and cut, without the buzz, and with perfect definition.
I hate to say it, but the Mark IV is just a better amp. :wink:
The Peavey cab might be a culprit aswell...not a clear cab, and can definitely mud up the Mark IV if you're not careful.