Starting from scratch in a large room

I am hoping to set up my first hi-fi system, but I have some room/equipment constraints and would appreciate some advice.

I am looking at an all-in-one amp and passive speakers. Right now, I am leaning toward a Naim Uniti Nova and KEF R3 speakers. I am a total novice and open to suggestions on both the amp and speakers, however, I do think an all-in-one like the Nova is the right direction for simplicity and space considerations. Other speakers I have considered are the Focal Aria 906 and BW 706 S2. I listen mostly to modern/classic rock, mixed with a little bit of everything, exclusively through streaming (preferably AirPlay).

The challenge is that I have a very large room, but I can’t use floor speakers or standmounts--the speakers will likely have to be on the built-in bookshelves, on a shelf that is 24" deep (it's not really a shelf, more like a wooden countertop on top of a closed cabinet). The room is 33’ x 18’ with 11-foot ceilings. I’ll be listening from either 13 feet or 25 feet. There are rugs covering most of the wood floors, heavy drapes on one of the long walls, and large canvas paintings hung on drywall on the other long wall. I understand I have some pretty major room limitations, but I'd like to have something that sounds as good as possible for around $10-15K. I've read somewhere around here that having two subs might help compensate for the smaller speakers. This is our living room/kitchen area, so I am limited in how many, if any, "treatments" I can make to improve the listening conditions. Would some kind of base between the speaker and countertop make a difference? Thanks very much.