How would you spend my next $5K?

Nice system.

Assuming you cannot remove the tv and all the equipment from between the speakers and dampen the walls behind with either dense wall hanging or acoustic panels. This should greatly enhance and deepen the soundstage and firm up imaging.

Then, first add a second sub. This will extend the sound stage and overall increase the dynamics. 
 

If you do not have direct lines, two direct lines. 

Not the analog rig - don’t start this unless you already have significant collection and significant desire to play it. 

Without listening to your system…hard to tell. But…

Acoustic treatment wouldn’t be a good investment. Upgrading the power supply on Mscaler could be worth it but shouldn’t be $5,000. Upgrade the amp may be?

#8, Whatever you are not happy with.

Why ask us? We don’t know your ears or tastes.

#7, expanding horizons.

As a long time LP guy, this is not a good time to start going deep into vinyl record playback. Records, even the crap I considered standard "used bin" that was 4-8 US dollars, is now 30 dollars plus online and optimistically graded. I buy mostly old records, and mostly obscure stuff. The new "audiophile" stuff is also pricey for what it is and there is a lot of bad vinyl out there. 

I agree that adding a second sub might improve your overall presentation. It is very hard for me to make recommendations without hearing the system in situ, how it is set up in the room and what is "missing." I would assume that your system does not commit errors of commission but omission. That's an assumption, though.

I guess the real question is-- where are you dissatisfied? 

I find audio reproduction systems require gradual improvements over time-- once you finesse the set up and know how the system interacts with the room, you can concentrate on improvements. I also don't buy into "miracle tweaks." I think you build upon the strengths of the system by looking to improve the weakest link. What is that, in your estimation, OP?