Why are my woofers pumping?

stereo5: I don't diss the KAB. I am only saying, single-ended cables from my balanced phono stage to my balanced preamp sound much poorer in my system, compared to balanced cables. So a filter, to become a plausible option, would have to be balanced. The KAB, in the current configuration, is only single-ended (RCA connectors). OK?

I have been in contact with KAB and another filter maker suggested earlier in this thread. They have responded very well and informatively. 

Two camps appear: the "purist" who say: fix the problem, and the "lowly ones" (plebeians) who suggest a filter "to be done with it".

Pink Floyd LPs  - a  quick test of woofer pumping
1 The original LPs from the first years, not so much, deep sound is not recorded.
2 Notably more deep sound - increased pumping - overall sound is better - step by step - on Atom heart mother, and early 70s LPs - reaching a climax on Meddle
3 Less woofer pumping but also somewhat limited, anemic sound on my remasters of Dark side of the moon  (i dont have the original here)

Another KAB RF-1 user with great results.  VPI Aries 3, Ortofon Cadenza Black MC, Manley Chinook SE, McIntosh pre and amp, Sonus faber Cremona Auditor Ms, REL B1.  Glorious music.

+1 miner42

Just a thought, what if you used RCA to XLR adapters? BAT makes some excellent ones. I have an original Harvest first pressing of DSOTM and the bass is very taut and very deep with no woofer pumping.  I also have a MFSL pressing which for some reason is much lower in volume with no pumping.   I wish you lived close by, I would let you borrow my KAB filter to try.

Thank you miner42 and stereo5. It may take some time, but i wish to try your suggestions. Although changing the arm or the cart might be optimal, no one so far knows for sure what works best in my system.