Buy High Pass Filter or KAB RF1?

Great insight on the y connector Al!

Also, I cancelled the order for the KAB because I now think it’s a cartridge incompatibility issue with my light tonearm since the dynamic compliance of the cartridge is a mere 6 causing the cartridge resonance to be 15-16 Hz.

It looks like I will be on the hunt for a new cartridge first. 

I posted the following in one of your other threads:

It appears that the Rega P3 is normally fitted with a Rega RB300 tonearm, which according to the listing at Vinylengine.com has an effective mass of 11.5 grams. Also, since the cartridge is made in Japan its dynamic compliance is probably specified on the basis of 100 Hz, rather than on the 10 Hz basis that is usually used by the calculators, such as this one. I would expect that its compliance at 10 Hz is **probably** in the rough vicinity of 10 or so.

Plugging a compliance of 10 into that calculator in combination with a tonearm effective mass + cartridge weight of 11.5 + 6.5 = 18 grams results in a calculated resonant frequency of 11.86 Hz, which is within the 8 to 12 Hz range that is often considered to be ideal.

But note the word "probably" in my statement. It’s hard to say for sure.

Good luck. Regards,
-- Al

Your calculation is wrong. Your nagaoka has 6cu dynamic compliance only when it’s measured at 100Hz just like all japanese cartridges.

For your calculation you must use dynamic compliance measured at 10Hz (not at 100Hz), this is a problem if you don’t know.

Convert 6cu @100Hz to 10Hz

6 x 1.7 = 10.2 cu

this is a compliance of your nagaoka at 10Hz , now you can use this data for calculation of tonearm/cartridge resonance. Actually it can be from 10 to 12cu compliance. The range of RF is 8 - 15hz 

@craigert I am having the exact same problem and dilemma about what to buy as you are! Wow...was about to post myself. I ordered some Harrison Labs "FMODs" (20 Hz high pass)..I plan to put one on one channel to start and see if I can hear a difference in sound. I hope they solve my woofer pumping.

My Focal Aria 906's are getting "woofer pumping" when I use my turntable as well.  I've tried EVERYTHING, it's not an isolation problem (verified by moving it all over and trying different experiments...and making a digitial recording from my 'pre-out' into a digital recorder and playing it back, the problem STILL persists!)
@stereo5 any idea what's actually causing the problem? I have the same issue as you can see above in this message :/

Ok thank you so I am in compliance. Plus Rega told me people use this cart with my P3 all the time. 
Will a KAB fix a feedback problem? Just curious. 
I thought rumble could be caused by feedback but I have somebody telling me a filter wont fix feedback.