Subwoofer rumble issue

I had the EXACT same problem.  Get some long cables, move the table, it'll fix it immediately.  My subs were on isolation platforms, turntable on a wall shelf with a symposium ultra under it.  I even borrowed other tables, nothing.  The turntable was in a room node and no matter what I did, nothing worked.  I moved it, never had another issue.

I’ve solved that feedback problem on many turntables by dampening the plinth. 

Try a different phono preamp.  I had the exact same problem and spent two years and a lot of money trying to solve it.  I relayed my story to a well known vinyl writer and he suggested I swap out phono preamps.  I was surprised when a friend brought a spare unit over and we hooked it up and the rumble/feedback immediately went away.  My preamp was later bench tested and measured perfectly, it just didn’t play well with my setup and stereo subs.  Good luck!

Interesting. I’ve been considering upgrading my phono stage anyway. Maybe this is the excuse I need to pull the trigger. Thanks.

Subsonic rumble filter! All better! I understand it’s a “bandaid” approach but it totally worked and my stereo sounds amazing again! YES!!! Thanks again everyone!