Speakers for room size that provide greater detail.

For that size room getting a speaker with a larger driver will move more air and sound more effortless, dynamic and imo real. Open baffles like spatial and PAP are good choices. I’d also look into Fyne audio. Listening to a pair of F502s’s right now in 16x20x12 room that opens to more space and they sound amazing for $3500. Sound gets even better if you move up the range. I got these about 6 months ago to see if I like their sound and I’m likely moving up to the 703sp’s in a couple months. 

With a 10 K budget, I’d be lookin at a new set of Legacy Focas SE’s. Their a bit more
expensive but your 2 subs with a set of Focas SE’s will FILL that room with precision dynamic sound, and their beautiful. We love ours and room size is similar.

I’m surprised the ridiculous Pure Audio Project "assemble it yourself" speakers are mentioned. Sure, they’re ridiculous, but I fell for the hype and bought a pair last fall (Duet 15 Horn 1) to replace my cool (for me) Heresy 3s...on stands...the 3s are a fabulous speaker with 2 subs including a new "99." Large room 18’ ceilings, blah blah. The PAPs (unfortunate abbreviation implying a gynecological event) are GREAT speakers. That horn projects for miles and with my 2 subs providing some extra mojo these things are clean and clear and, frankly, have made me a better person and even thickened my hair. Who knew? I added the recommended silver/gold/oil gigantic Mundorf caps mostly because they look so cool, and sprung  for the possibly unnecessary Isoacoustics Gaia 2 feet...again they make it look like I care. Buy these speakers...do it now...we’ll wait right here. Note to the admin...put recent responses AT THE END OF THE POSTS like you used to! Come on!

I think your weakest link is the Rotel amp. For $5K you can get some much better, including Hegel, Moon by Simaudio and Anthem. Also, that room is large; do you have acoustic treatments? With two subs, you might be muddying the sound without bass traps. Also, you state that you are 15' from the speakers; that seems possibly too far away for standmounts, but you don't say how far away from the backwall they are. The triangle rule is that the speakers should be the same distance apart from each other as you are from them. A 15 foot spread between mintors seems too large, so it might just be your current setup, which won't cost you anything to adjust. Good luck

#ghdprentice "If one is going to do a major upgrade of a system, speakers are a place to start. Get the very best speakers you can that appeal to your ear. Then upgrade the other components to support the speakers and achieve the kind of sound you want... the electronics are a big factor in how dry, or musical, or analytical or dynamic you system sound. So, if this is your plan... speakers are the best place to start."

Here I respectfully disagree with your post. The old adage "Garbage in = Garbage out" is still apropos here. A high end speaker will not sing properly if not fed the right input. The Rotel puts out a lot of power at 200WPC, but it is all AB, no A/AB. I cannot find it’s stats into 4 ohms, so I’m guessing that it doesn’t nearly double, which would explain why people describe it as dry & sterile. I have Martin-Logan ES hybrids and have listened to an amp that only had 50% increase into 4 ohms and it left them flat and lifeless. High current is where the details lie, not the WPC. To the OP, try my suggestions above, and then get in in home demo of a nice power amp (maybe even tubes/hybrid) to see if that helps.