After messing with heights of some M5 bookshelves and noticing the tactile impression change in my 2ch room I was inspired to experiment with raising my subwoofers behind the screen in my theater room. I have dual subs at a front wall 1/4 width setup with the face of the subs 28 1/2” off the front wall. This leaves 12” of space behind them.

I raised the subs to 37 1/2” to center of driver to match the tweeter heights on my diy towers in a WMTMW vertical configuration. I used cinder blocks stacked, opposing the direction with each course to add stability. The blocks are literally “rock solid” and the net wight of each stand is about 320lbs. It took 16 blocks to build two stands.

They are 3$ per block. Best upgrade ever.

I did not get the low volume tactile presence as I get with my M5s, but the low end is so tight and nimble now. I thought it was great before (and phase plots agreed.) I ended up watching a demo movie all the way through by accident. Music is really improved as well. It was one of those upgrades I didnt know my system had. You think you are top notch.... then you find another notch. Lol.

You will need to bump up your sub level a few db to account for uncoupling from the floor.

Highly recommended tweak if your system has allowances for hiding subwoofers out of sight.