I found Herbie's Tenderfeet made a nice difference under my tube integrated. If your receiver is over about 45 pounds you'll need something more heavy-duty though.
Best isolation under a big receiver ?
I have found the gingko cloud to be great under my cd player, and am perfectly satisfied with it. But i have nothing under my big b&k avr307 receiver except the shelf it sits on. I know it is not as sensitive as my source, but i would still welcome your thoughts.