I used a Cartridgeman moving iron cartridge with a Hadcock arm. The isolator was created to use with them and although I heard it i never bought one.
If you are having problems with subsonics I doubt this is the cure.
You'll need to give more information about your system and how it is positioned. Have you got the turntable next to the speakers or in a corner? Is your room full of soft furnishings or sparsely decorated? What is the turntable some of them need really good isolation to work properly.
Thorens TD550, Ortofon 12", Ortofon Jubilee or Koetsu Black; Rothwell MCL SUT, VTL 2.5 pre, XTC POW 1 power; Naim CD5x; KEF Reference 3.2's; Van den Hul interconnects and speaker cables.