I have a Technics SP10MKII mounted in a birch plywood plinth on a mdf shelf attached to wall brackets. The turntable is sitting on four blue racquetballs, which eliminated the acoustic feedback I was getting. I'm planning to try IsoBalls or another Herbie's product to see (hear) if the offer any advantage over the racquetballs. I'm planning to upgrade the wall shelf as well, but I don't know if I should use a rigid but light shelf (e.g., Ikea Lack table top,) a mass loaded shelf (i.e., slate since I have an appropriate sized piece,) or maybe a maple platform? Should I use some isolation material to decouple the shelf from the wall brackets or attach them firmly?