Woofers Gone Wild

Most likely culprit is rumble. I had the same problem and got the KAB filter referenced in the first response to your post and never looked back. To be fair, you should examine a mechanical solution to your problem first (compliance, damping, etc.), but it might very likely be the pesky rumble that's so common with vinyl causing the problem. If so, get the filter; your woofers will thank you and you'll be able to sleep at night.

I understand the sentiment of the purist approach to this problem, but I wonder how many of the purists actually used the filter and can offer meaningful advice. Saying it filters ergo it wrongs the signal is, in my opinion, a simplistic theoretical approach that does little to shed any light on its actual real life effect. I've been using the filter for a few months now and don't look back. I have no doubt that the woofer fluttering caused more deterioration to the sound that removing frequencies from the signal that can't even be heard. And warps often have little to do with the fluttering; the worse woofer pumping I noticed happened with a perfectly flat 200 gr record. And yes, my cartridge/tonearm matching is spot on.

Atmasphere,
So what do you suggest for those whose cart and tonearm matching looks correct, at least on paper, but still experience woofer fluttering?

The test record and my calculations both put the resonant frequency of my tonearm and cartridge combination above 9 Hz, which I understand is considered correct. My phono stage is from the same manufacturer as my cart, and matches the recommended capacitive and resistive load of the cartridge. I realize it's a complex issue, but reasonably can anything else be done, I wonder?

Atmasphere,
My speakers are the Totem Acoustics Hawk.

Eldartford,
That's my understanding of the filter as well. I've personally noticed absolutely no deterioration in sound since I put it in the signal path. In fact, I think it has improved the sound.