Suspension vs. non-suspension turntables???

Hmmm. Just because something's old doesn't mean it's time to change it. In fact you might find out it's shockingly expensive to change. My rega planar 3 cost me $300 many years ago when I lived not far from Southend in the UK. I think I'd be spending well over $1000 to get a significant improvement in it now, and that's money better spent on a new cartridge and more LPs or CDs.

I'd guess you'll get better advice if you can tell us what improvements you're seeking versus the roksan.

I've only ever owned non-suspended designs, so I can't answer your question.

The concrete floor suggests to me that a floor standing rack would work well. My guess is that the drywall is picking up the bass and feeding it into the wall rack.

A very cheap setup for isolating my rega is a sheet of soft polyurethane foam, about 2-3 inches thick, with a large paving slab (or marble sheet if visuals are important) sat on top of it, with the rega sitting on the top.

I have not noticed any bass feedback from my subwoofer, and my spirit level says the deck is very level (the mass of the deck is much less than the concrete slab so levelling was easy). My floor is a wooden suspended floor, and the subwoofer is only a couple of feet from the Rega.

Of course the weight of this setup means it has to be on a cabinet, rather than a shelf, but it costs so little to try (about $10-$20) that it might be worth playing with before getting a new deck.

That is, unless you really want a new deck. Buying a new deck is much more fun than buying paving slabs :-). Until the credit card statement arrives :-(