Damping sheet tweaks
I read about tweaking the top cover of the Jolida JD9 phono preamp with damping sheets from Parts Express. Not only did they work great to dampen my Jolida's sheet metal, but I used them to dampen the wood platform for my TT. I have my TT sitting on a wood platform which rests on top of Vibra-pods and cones, which is placed on top of a record shelf. I applied the damping sheets to the underside of the wood platform, and it make a HUGE difference. Every aspect of my TT's sound improved.
The damping sheets are self adhering, and cost about $10 for (4) 12x12 sheets. I highly recommend you get some and experiment how it can improve your system's sound.