I'm somewhat embarrased to say, that a few years ago I was 'experimenting' with a couple of Naim pre-amps, a 122x and a 202(x?) (both garbage btw), and both had 'floating' main boards. They, Naim, even went so far as to say in the owners manual that movement of the DIN sockets was normal and supposed to be that way, as they believed that a floating MoBo gave better sonics. Maybe this is where the OP is getting his ideas from?
Having said that, and I'm in no way endorsing or agreeing with the practise; the bat sh*t crazy people at Naim also have a machine that SHAKES their cables - yes, all it does is hang the cables vertically in a tall frame and shake them vigorously; again claiming sonic benefits!
There's also someone on the tube (! where else!) who recomends that rear panel sockets on DACs and pre-amps should have their retaining screws loosened slightly so they don't 'grip' and hold them securely to the circuit board they're attached to, claiming real sonic benefits from decoupling the sockets from the chassis. This is easily done should anyone wish to try it, as it's easily returned to standard.