my method of speaker toe-in and rear slant, thus inward and upward directivity, is part of why I don’t seem to get vibrations on the surface of the LP between/behind the sealed boxes I think. Your setup may be part of the solution, or .......
My SUT to select which arm and impedance or PASS for MM just fits under the side of my TT, (normally I can see/move it’s two selector knobs, shown pushed too far underneath the TT here) I have to move my Preamp/Amp cabinet to work on it. Notice felt squares on the end of the dust cover
It’s big, you need to plan for where it goes during play, some covers would be huge, it may determine where you place other equipment, it did in my setup.
Some more felt on the face of the Reel to Reel Tape Player protects the cover when using the TT. Below, prior setup, SUT was on a shelf below the TT, actually harder to see the various markings, hard to position, but better now.