Mick Said:
... and also I am toying with the idea of having having a special bespoke Townshend Seizmic air support made to place under the plinth.
I've had my 401, now in a Bastin Plinth and on a Hutter Stand, in another homemade Bastin inspired plinth and on two other kinds of Stand,
I believe what is important for the 401 is to ensure that any motor vibrations are first attenauted, by, e.g., an uprated power supply and secondly evacuated fomr the plinth asap. If possible without intefering with the arm/platter connection.
I've tinkered with various intermediate supports, such as laminated glass shelves on vibrapods. Now I think, that if you have a first rate stand, such as Hutter, the advantage of tinkering with intermediate shelving is limited. Having said that, I can't comment on what a seismic or voodoo platform might do for the 401. I know that in the days when I had a less than first rate stand (Ikea/Ash Design) hard feet on the plinth sounded worse than rubber doorstops. In the end 2cm diametre, 1cm white runner door stops were the best feet I could find. Now with the full, latest, spec Bastin plinth the rubber feet are smaller but I wouldn't want to go with hard feet, such as oak cones, because I think the rubber serves as a barrier to transmission between stand and plinth.
Of course with a Loricraft plinth, which has squash balls in the plinth, hard feet may entirely be the way to go.