Spring isolation worked wonders for me.
https://www.amazon.com/Nobsound-Aluminum-Speakers-Isolation-Amplifiers/dp/B07K9ZYP84
I used the iso-acoustics, but there are a bunch of cheaper options for isolation These seem to review well https://www.amazon.com/Nobsound-Aluminum-Speakers-Isolation-Amplifiers/dp/B07K9ZYP84
EDIT: I was just reading the spec on the nobsound, and they are rated at 40lb each, a bit much for a turntable. Probably better off with an Auralex Pad or the IsoPuck