There is a preferred course in high end audio is to fix the problem… never cover it up. Covering up problems makes it worse.
I highly recommend identifying the source of the rumble and just get a great phonostage. I would look for a used Audio Reserach PH8… a real classic, incredibly good sounding.
I have had phonostages ranging from $200 and $17,000. While my current is best… the PH8 was an incredible value.
If you could show photos of your system under your UserID I am sure we can figure out why you think you need a rumble filter.