You might want to try adding Stillpoints under your table. These seem to have a very strong following for providing amazing enhancement to turntable support.
Another idea would be to add a Sistrum support. I recently added one uner my Teres 255. My teres sits on top of an Adona granite slab that has a substrate underneath to better absorb resonance from the granite. Then I have the sistrum between that and another granite slab ontop of a wall mount shelf. I found the wall mount to be a significant step up from any traditonal floor mounted rack, especially because the house I'm in is on a suspended floor. I'd be surprised if your wall mounted shelf is the culprit.
Another suggestion echoing others is to get a new preamp/phono stage. The biggest thread on Audiogon is the Preamp Deal of the Century thread about the Supratek preamp. Getting a Syrah or Chenin from Supratek might really catapult your vinyl to the next level.
Another idea would be to add a Sistrum support. I recently added one uner my Teres 255. My teres sits on top of an Adona granite slab that has a substrate underneath to better absorb resonance from the granite. Then I have the sistrum between that and another granite slab ontop of a wall mount shelf. I found the wall mount to be a significant step up from any traditonal floor mounted rack, especially because the house I'm in is on a suspended floor. I'd be surprised if your wall mounted shelf is the culprit.
Another suggestion echoing others is to get a new preamp/phono stage. The biggest thread on Audiogon is the Preamp Deal of the Century thread about the Supratek preamp. Getting a Syrah or Chenin from Supratek might really catapult your vinyl to the next level.