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.

Check out Townshend Audio Website for reviews, i use the big Sound lab Dynastats i could never get the bass right until i put them on the Seismic Podiums the results are jaw dropping , you can buy from audiogon for sale pages good luck you will not have any further bass problems and you will hear your speakers like never before.
I agree with Mofimadness and a few others that you may be dealing with "acoustical  feedback".  I had the same issue in a console. My turntable was producing a lot of hum when using my turntable and turning the volume anywhere past 11:00. I ended up getting an amazing isolation platform from  Symposium called the ISO Segue! It solved the problem immediately- quiet as a mouse!
Even though my turntable was on a wall bracketed shelf, I still got air-bourne feedback. The woofers, especially my subwoofers, would be oscillating, and I also saw my tonearm bouncing up and down -- not out of the groove, but it was pretty peculiar to watch.

I used a KAB rumble filter, added more methods of isolation under the turntable, even between the wall bracket and the wall itself. The only other thing that comes to mind is isolating your turntable in another room, but then you would have to get up everytime to tend to it.

Best to you in your rumble and feedback endeavors -- hope you can solve your problem.
Townsend's research looks pretty convincing. £1400 asking price does take the breath away :O
While I was browsing the Townsend I happened to notice someone with a pair of Montis was actually using Podiums to solve the OPs problem!
It looks somewhat floppy. I'm not sure I'd risk tall speakers on it.
Nevertheless they claim good results which seem to be backed up.
I would look at my tonearm alignment.  If the VTA is off, you'll get overwhelming bass.  Assuming you have a VPI unipoint arm, they are very good, but very difficult to set up.  Look at the arm as you track a record and see how it looks.  Make sure the azimuth is set correctly, the stylus is 90 degrees in the groove (cartridge isn't 'listing' to one side).  Look at the base of the tonearm and make sure that is balanced perfectly and not listing as well.   It should appear as its floating, not dragging.