Why are my woofers pumping?

vpi, and others - two camps in this thread, "fix the cause" or "fix the problem" - if I want to fix the cause, and change the tonearm, keeping the Atlas, although I dont have the financing to do it now - what would be a good match, with a resonance around 10 hz? That sounds good with the cart?

One more test. Changing the connectors from the Aesthetix Io phono stage to the Einstein preamp from balanced to single-ended. Result; much less woofing with single-ended. But much poorer sound too! More flat, congested, less involving. Even when I turn the volume up, to get the equivalent decibel level (which I have to do, for the single-ended connection), there is less "here-ness" to the music. I have a semi-balanced phono stage - balanced from the second amplification section through the output. The balanced outputs sound way better than the SE / RCA outputs. Conclusion: a single ended filter like the KAB probably will not work for me. Running the phono signal single ended, or through a single ended tape loop, will degrade it.
Cables used for testing: 1) balanced - JPS Superconductor 3 (very good xlr cable); 2) single ended - Kimber KCAG (very good in some applications but not here).

Status: I enjoy my SME V / Atlas combo, even with some woofer pumping and - maybe - possible distortion. Yesterday I tested Kula Shaker: K2, on LP vs Tidal digital. Result: digital = no clear woofing (as before), but poorer sound. Distortion - some, very evident in loud music passages, from both sources, but overall more "grunge" in the digital. The contest was a bit more even, than I remember - analog does not totally outcompete digital, but still, no doubt. I should probably consider a better DAC. But if it has real "grunt" (like the Aesthetix Io) maybe this includes some woofer pumping ;-  If you cut low frequency it easily hurts ambience, overtones, etc. I think this is why Pink Floyd's Echoes has woofer pumping. Everything down below is recorded. The vinyl is taxed to the maximum. You can hear this deeper tonality also in the high frequencies (Richard Wright playing light organ touches). With today's resolving systems, we are able to reproduce such pioneer enginering efforts and should be grateful for it.

You keep coming back to the KAB, then diss it.  Why not get one and try it?  If you don't like it you can send it back.  I use one in my system and my 3 audiophile friends and I could tell no difference with or without it other than absolutely no woofer pumping.  The Turntable is a VPI Prime with a ZU-Dl103mc cartridge, VPI interconnects going to a 7K McIntosh tube preamp.  Speakers are GE Triton Reference.  Like I said, problem solved and I can sleep at night.

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".