Kip,
In the past, I have had some success using laboratory equipment isolation equipment (Herz, Kinetic Systems (the makers of Vibraplane), Shima-Koki, etc). This lowers the resonant frequency of the TT base to 2-3Hz in both the horizontal and the vertical plane. The air suspensions require 'maintenance' (filling/topping up the bladders every now and then) but it's easy. If you go for the truly active suspensions, they cost a fair bit more money (though some swear by them). They can be found used on 'that other auction site' for a lot less than new.
In the past, I have had some success using laboratory equipment isolation equipment (Herz, Kinetic Systems (the makers of Vibraplane), Shima-Koki, etc). This lowers the resonant frequency of the TT base to 2-3Hz in both the horizontal and the vertical plane. The air suspensions require 'maintenance' (filling/topping up the bladders every now and then) but it's easy. If you go for the truly active suspensions, they cost a fair bit more money (though some swear by them). They can be found used on 'that other auction site' for a lot less than new.