I had 3 different VPI turntables, a HW19 MK4, Scout And Prime. All 3 of them neccistated a KAB Rumble filter. Like yourself, I couldn’t move the turntable from its position. I tried everything I could think of, 4 different types of platforms, different kind of footers, etc. Nothing changed the rumble. Recently I switched to Technics SL1200G turntable, using the same cartridge and lo and behold, no more rumble. It must be something in the design of the VPI tables that helps amplify the rumble. At any rate, I am very pleased now.
Why don't all phono preamps include a rumble filter?
In my system, the use of a rumble filter is mandatory (I notice no degradation of sonics when I engage the rumble filter). I'm thinking of upgrading my phono preamp and would like to choose one that has this as an optional feature. However, it appears that most manufacturers of phono preamps do not include this. Why not? Does the use of a rumble filter degrade the sound of a phono preamp?