Turntable isolation advice needed

[Mouse]

I have a new Dr. Feikert Blackbird turntable, it sounds great until I crank up the volume. Now I'm looking into isolation.

I have a Solidsteel HY-4 rack.
Am I better of getting an isolation board to put on top of the rack/under the TT?
Do I change the feet?
Do I put isolation pucks under the feet?

I love my TT, but here are some of the defects. At >50% on my MC8900, I feel the table vibrate some, probably robbing me of a little sound quality. At around 70-80 I start getting some low end feedback while playing music, and when the music stops I can hear my footsteps through the speakers in a form of bass.