Elevating subwoofer about two feet off the floor

It is just a frequency response thing. If you had room control you could make the woofer sound the same and be more efficient and probably go even lower. If you have control of frequency response on the floor or in a corner is always going to be better. But if there is a response aberration and lifting the woofer helps and you have no other way of dealing with it you are stuck.  

I have a Rythmik sub and so far its has been sitting on the floor spiked with moderate results. I have done measurements using REW and there were a couple of suck outs and FR was not even. After reading this thread I decided to try it out so with the help of some stack of books I raised the sub 12" off the floor. Did my measurements again and was surprised to find that all the suck outs were gone and now the FR was pretty much flat. Adjusted the phase, xover and gain and I am enjoying a sub that is very well integrated with my monitor speakers. Its worth trying it out. 

Never hurts to experiment.Another thing to try is turn them to face the wall and move them closer or farther and hear what happens.

Have your cake 🎂 and eat it, too. Isolate the subwoofer with springs. Then you isolate the front end electronics from mechanical feedback AND take advantage of the proximity to the floor. Problem solved! 🤗 I’m pretty sure isolating the sure also reduces cabinet resonance. Three, three mints in one! 😀