Audio diffuser

My room is 14x22x8. Speakers are about 19in off the front wall 1.5 from side wall.  I sit 13 feet from the speakers. They are not toed in. i have a fantastic sound stage with 90% of sound coming from the center. It's just on some music the treble gets a little hot on my ears. Bass can be a little weak at times. Thats why I  thought just the 2" depth. Just enough to break up the high notes. 

Haven't determined size yet. I have bass traps and absorption on the back wall and sides. Dedicated music room. Can't do just the center as I have a TV hanging dut covered when not in use. 

@knighttodd , sounds like a well damped room so far. I also went 2" behind and to the side of speakers, I need all the bass I can get.

I don't know how much the high-end will be improved by your new diffusers. There's mostly backwave from speakers, your bass will probably tighten up and image may become more focused. For highs you may need to treat the ceiling.

Am I wrong in thinking those stands look short. Typically mini monitors are elevated to ear level when sitting. Are they? Perhaps you have experimented with different heights.  

Update on the install. I installed 8 of the 2" deep wood trays. 4 on each side behind speakers.  4 more, 2 on each side of the back wall.  There is a decent amount of reduction in  treble glare that I was experiencing with some music. Overall it has smoothed out the room and the bass seems much more clear. Very easy to install. Inexpensive and well worth it for high-end glare. My system consists of  Lumin u1 mini with sbooster, Roon Nucleus, AR Ls28se, Audio GD r7he mkii dac, Tyler Acoustic Halo Extrem speakers and 2SVS pb300 subs. Prima Luna Evo 400 Amp. My system and room has been 2 years in the making and this is the best so far.