Woofer sucking in and out

I have a problem with my analogue set up that once it starts play, the woofers of my speaker will move in and out like crazy, unrelated to the music! It relates with volume as when the volume is low, the woofers will not move as much. May it has to do with oscillation between cartridge and arm but my set up is new. The turntable is Acoustic Solid-Transparent and rega301 arm with cardas wiring and weight mods, Herron VTSP 3A pre and VTPH phono. I wonder if placement has anything to do with it or power connection.
I hope someone who has the same problem before can give me some hints.
The KAB unit does NOT effect phase. Period. Call Kevin at KAB he will be happy to verify and explain this, but here's technical info from his site:

"1. When records are made, frequencies below about 150Hz are combined to mono. This is done to avoid large out of phase groove excursions.
2. When the stereo stylus moves vertically, the two signals produced are equal and 180 degrees out of phase. Therefore, below 140Hz, the music is in phase in the lateral stylus motion, and only out of phase noise is found in the vertical stylus motion. The KAB RF-1 takes advantage of this by electronically combining the left and right channels together below 140Hz. In so doing the filter effectively cancels vertically modulated noise. Vertical rumble comes generally from bearing noise of the disc cutting system. But since the music below 140hz is already mono on the disc, the musical information is unaffected. Below 20Hz, all signals are quickly attenuated at 18dB/Octave."

I have many records that cause this phenomenon with my ported Usher X-718s and it is not an isolation problem (record a bit of the LP to CDR with the speakers off, play back the CDR and see if it still does it, if it does it's not an isolation issue), my cart is perfectly matched (resonance of 9hz). The KAB solves it.
Vinyladdict, just for the record (if you will pardon the pun) I have a Westerx LP mastering system, and it does not do any mixing whatsoever of the channels at any frequency, and every attempt is made in the design of the cutter itself to enhance stereo separation- at all frequencies.

Now I can't say how other LP mastering systems work- I only have exposure to my own- but the Westerex 3D cutting system did a lot of the stereo LPs made in the US. So I am regarding this comment

"1. When records are made, frequencies below about 150Hz are combined to mono. This is done to avoid large out of phase groove excursions.

with suspicion.
Of course it doesn't have to be done but very often and more often than not it is. It's a common practice that has been around since the dawn of stereo - do a search for "LP mastering 150hz mono" and you'll have enough to read for quite some time on the matter.
Vinyladdict, All filters affect phase. Period, end of story. As was said earlier, a filter is a band-aid. The OP needs to find the source of the problem and address it.
Just because you experience this phenomenon doesn't mean there's a problem to address. Period, end of story.