Subwoofer bass issue

Hello all,
Looking for some direction.  Here is some background....small / medium dedicated listening room, 16' x 11' x 10'.  Set up on long wall, heavily treated with absorption (side walls and behind listening position)and diffusion(front wall behind speakers and rear walls) bass traps in corners.
McIntosh 601 monoblocks, C2300 tube preamp all on anti vibration rollerblocks and platforms, hi end Synergistic Research cabling and power cords, Sonus Faber Guarneri Evolutions paired with two REL G-2 subs....
Beautiful full soundstage with tons of detail and body, extraordinary bass...just what we shoot for right?  Problem is on certain tracks on certain albums, Dianna Kralls Turn Up the Quiet for instance, I get this crazy bass rumble that sounds like a small train going by the room.....weird thing is that on albums that the sound engineer obviously tilted up the bass output, Patricia Barber Modern Cool or Rene Marie Sound of Red, sound just awesome!  No issues.  I have experimented with moving the RELs further back, further out, closer to the mains or further from the mains and I can't seem to eliminate it.  I have stone floor over concrete with 1" thick wool rug just in front of speakers and covering most of the floor.  Recently tried "decoupling" the subs by placing them on roller block bearing devices and it help some....BTW, shocked on how beautifully this tightened up the bass in general...just didn't eliminate this occasional issue.  I tried turning down the REL output from my typical setting of 18 down to 10.....stops the problem but takes all the body and bloom with it...has anyone out there experienced this and how did you solve it?  Open to suggestions.
Thanks as always!