Without the GEQ, I find all of the Mark 2’s and beyond sound honkey with too much mid range. For me it’s not even fun to play clean without the GEQ. Speakers didn’t matter either. I have EV’s Eminence MS-12’s, and all Celestion speakers.
Having owned the custom stereo GEQ made by Mike B (as well as having the studio PFE modded to isolate the GEQ) I tried bypassing the onboard GEQ and adding one back into the loop. It made the amp a bit mushy and never had that throaty sound.
Here is a pic of my old rack with the GEQ
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