Bass distortion-Playing LP's only,,,,please help


VPI Prime----Ortofon Black Quintet (low output moving coil cart)-----Plinius Koru Phono Pre( loading at 20 ohms/gain at 66 db)-----Parasound Halo Integrated -----Martin Logan Montis speakers which have powered bass cabinets.

Using any other source component I have absolutely no issues. When I play an LP and increase the volume past 10 O'clock which is a little loud....but not ridiculously loud-I at times get this huge wave of bass distortion. I do have bass controls on the Montis's...and I have turned them down into the negative, but I still get what I previously described occasionally. 

Any and all help would be appreciated. This doesn't always happen, but its frequent enough to drive me crazy.

Thanks in advance.

krelldog
Agree with most folks here - very likely acoustic feedback.  First choice of potential fix - move the tt further from the speakers.  If the speakers and tt both sit on the same suspended frame wood floor, this can be a bitch to eliminate.  If you can get them on two different flooring structures, you're way ahead in the game.  I know that's a big "if", but it's the best way to go whenever feasible.
Anvil turntable footers completely solved my acoustic feedback issues.  I agree with trying to move place your table farther from the powered woofers if possible. You never know how much better it might sound.
it's not acoustic feedback to worry about it's EM resonance between cartridge and speakers

Czarivey said :-

"It's not acoustic feedback to worry about it's EM resonance between cartridge and speakers"


This is nothing more than scaremongering. You'll find most audiophiles, including myself, will have learned to place sensitive gear e.g. CRTs and magnetic cartridges, at least 2ft from unshielded loudspeaker magnets.

MLs are magnetically shielded.

If you have both min clearance and shielding, case closed.

@moonglum , Didn't I mentioned Electro-magnetic resonanse?

Do you have any idea how heavy the ELECTRIC field of panel speakers? They can cause not only rumble but even ED when you hang around too close!