Ready to RUMBLE

Perhaps not a direct answer to your question but here also rumble problems.
VPI Scoutmaster Signature/Benz wood SL/Nagra BPS/Quad 99 - no subsonic filter.
50% of the lp's are OK
25% are more or less OK
25% are bad
So I think it is not the system.
I don't know why people call it "subsonic" ; I can hear it very well if a record is bad.
Been looking around for some external subsonic filtre but not much choise available.
The KAB RF1 is a possibilaty but I'm not used to buying in the US (I live in Europe)and I fear that it will influence the sound.
Any advice appreciated.

KAB rumble filter. Google it. It works.

You should try Theo's advice and attempt to eliminate the rumble mechanically. If it doesn't work, I recommend the KAB rumble filter, which at a very reasonable price will eliminate rumble and might actually improve the sound by relieving the amps from trying to reproduce infrasonic frequencies, and removing the unnecessary and possibly harmful fluttering of the subwoofer.

I also own a P9 and a C2300. I have hardwood floors and a large KCS basshorn in my room. I had a rumble issue prior to installing a rega wall shelf. I previously had my P9 on a 3 inch maple slab with brass points on a Billy Bags stand. Now I do not have an issue thanks to the isolation of the shelf. I recommend that you attempt to isolate your table via a wall shelf prior to installing a rumble filter in the signal. Make sure that you mount it directly into the studs.

Thank you Rich62. I am finding most of my issues are LP related and not hardware related.