System recommendations

I agree with @stereo5 that the biggest improvement will be in your speakers which may be the weak spot. However, I also agree with @ghdprentice in the importance of the preamp. And this too is a weak spot. Which is the biggest bottleneck is hard to say.
You may be surprised at how much more  Rel subs can add to the speakers. They magnify not just the bass but the whole freq range This makes for much better imaging. So that may be your best option. But at some point you need to upgrade your preamp. Tubes should be considered

You question is a tough one. You have, I think, a very good system. Really difficult to find fault with it. However you are expressing a desire to improve what you have. This is a clue for me that you really want to make a substantial change. With that in mind, it's time to shop for new loudspeakers but perhaps wait to purchase until you move into your new space. You want to make a big move up, avoid making a sideways change, it will not satisfy. 

@stereo5 
I have never heard before that Mondial had anything to do with Mark Levinson. Mondial was a small company out of upstate New York. To my knowledge, Mondial made only Aragon and Acurus products. The 4004 amp by Aragon was considered a poor man's Krell, because supposedly Dan D'agostino had a hand in the design. 

Never the less, the 8008 was a very good amp with ample clean power. I have owned multiple Aragon amps over the years and the 8008 is likely not the weak point. The Aragon preamps were not held in as high regard as their amps. I have never owned one of their preamps, so I can't say if that is a bottle neck or not.

Looks like a well balanced system.
IMHO, the best bang for the buck for an improvement after the room treatment is to upgrade the preamp. Changing speakers will bring more change, but at higher cost.
However, you might want to have a long term plan to upgrade the whole system (which will cost at least 20K for a new system and 10K for used).
For example of a used system, I have Plinius SA102 (2K), Audible Illusions M3B (2K), Oppo 105 (1K), and Gershman Avant Garde (6K). Such system will definitely sound superior to your current system.
My 2 cents.