Improving sub quality

I have my HT subwoofer floating on Aurios MIBs 1.2 and this has improved its performance significantly. The Aurios could be bought on the gon for approx. $200 or less used. You would need a hard surface for the Aurios to sit on though.
Good luck.

I have a REL on carpet on a suspended wooden floor and it sounded worse on spikes. It surprised me, but REL generally recommend against spikes, so perhaps they know better.

I have found the best room loading to be out towards the middle of the room (just in front of one of the main speakers, following a Cardas placement method). REL's corner placement always sounded boomy to me.

When it comes to placement you'll have to decide. Obviously major differences between all of our rooms and preferences. You may want to read about room acoustics if you haven't. A bass trap or two can do alot of good when you have honest bass down low.