You have the real-estate so I would put the equipment on the floor. On thick dense boards. On spikes. I would place the speakes on fits from the side wall and thirds from the end wall. Quarters if you want mid bass. I would look at your receptacle s. I looked for bass in my new room I had nothing and I mean nothing changed out the industrial 20 a.p plugs for furutech plugs started with the ones at the amps and I got some bass. Did the ones at the side where the rest of the equipment is got a bunch more. I was shocked at the difference in bass as well as transparency. Guess your shelves us the receptacle s are causing the problem. Speaker placement on thirds the speakers need to be almost 11 feet out into the room on foths you need to be six feet out into the room give them room to breathe. A d yes treat first and second reflection points I like mainly diffusion with just a small amount of suction I tent to like the sound of a live room and dislike a dead over absorbed room you will need a bit of absorption though. Basically in my opinion you have to go find your bass you don't have to spend any huge amount of money you need to find it. You have good gear and nothing needed there just have to find the bass. Powercords maybe the problem as well. But I would look at that way way down the list.
Regards