Speaker placement

Hello all, I do not have a dedicated listening room. My system must be in the living room with all the usual furniture. This keeps my speakers only about 18 inches off the wall, with a large heavy 30 inch tall media center in between them on top of which sits the electronics. I am not unhappy with the sound but I know that this is not the optimal set up. I have recently been reading about omni speakers such as from Ohm and Decware which are designed to be near the wall. Does anyone here have experience with them? My system is Prima Luna Dialogue Premium HP at 70 watts, Nordust Red Dawn into Tekton Lore speakers. Room is 15 x 23 with vaulted ceiling from 8 to about 20 feet with open walls to other rooms. And I play loud, turn volume to 2:00 or 3:00 sometimes. I listen to everything from rock to blues to jazz to easy listening to classical, but mostly love trying to feel like I'm at let's say sitting up front at Pearl Jam at Madison Square Garden. Thanks for reading and any thoughts.