Turntable and subwoofer living together in peace and happiness

The first thing that struck me looking at your photo is the wood floor.  Wood floors are notorious for transmitting vibrations.  Is the floor spungy at all?  If so can you brace it from underneath to make it firmer?  That would help.  Also, underneath the speakers I have found Isoacoustics Gaia isolators are very helpful.  I also used them underneath my TT, but whatever you choose, some sort of isolators directly under the TT would help in addition to what you have already done.

Get thee a Preamp with a rumble filter; Low Cut Off Filter, they were designed for exactly your problem.

I have to use mine in my Vintage Preamp when playing my Shure V15VxMR that tracks at 1 gm, and it is mounted on a ’too heavy’ arm best for medium compliance cartridges. When a big warp hits, a light tracker, with a too heavy arm may even get yanked up out of the groove.

Wood floors, mine are like a Flexible Flyer, my final solution, (after all the weight of your stand is level/down, no forward weight when the floor flexes), is a set of isolation blocks 

My light trackers, I have to tip toe away, you develop the skill of just getting your lifter started down, and get out. Steve at VAS is going to change the fluid in my Vintage JVC Victor UA-7082 arm lift that drops too quickly.

btw, are you sure your arm and cartridge compliance are good together?

OP, there are many threads on this topic. Just do a search, then ask questions. Respectfully.

I have a Clearaudio Master Innovation and use large floorstanding speakers and a six-pack of REL S/510 subs. 

I have no issues whatsoever with bass feedback/woofer-pumping, but I have also invested in great isolation (HRS EXR rack + HRS M3X2 isolation base for the turnable).

I have old wood floors that aren’t braced, I don’t use platforms under the subs (they are designed to couple to the floor anyway), and I don’t bother using the 10Hz low pass filter on my phono-stage. However, the Rega Planar 3 and my Clearaudio TT are very different animals.

Also I don’t have to tip-toe around the room. If a record is playing I have to jump up and down enthusiastically to upset the cartridge tracking...and it still doesn’t skip. Footfalls from normal walking around are inconsequential.

I’m a firm believer in isolation. I treat it as a component of equal or greater importance to everything else. I’ve also been down the road of DIY isolation solutions (that really aren’t effective enough, if at all)...sorbothane footers, hardwood cutting boards, or both blah, blah, ad nauseam. I never solved those problems until I invested and left it to the pros.

Your problem is lack of a rumble filter most likely. I have one of those highly maligned Technics SL-1200MK2 turntables with a Goldring E3 cart. Not exactly high end, I know. It sits on top of a 3-tier glass unit all in a room with wood floors.

I can play albums at any (reasonable) volume with zero effect, No T/T isolation required. I run dual HSU subs and a 330 watts into 4ohm amp. Plays clean as a whistle.