Best set-up under $20K

B&W Speakers are interesting for me.  The first one's I really heard a difference on were the 805 Diamond's from the early 2000's.  Since then I liked other sonic profiles better and have been able to hear more differences in electronics with other speaker brands.  ProAc, Magnepan & JM Reynaud being 3.  I like a warm seductive nature, not muddy though, & nuances of music better than purely analytical sounding system.  From what I've read and heard at shows and demo's, the MacIntosh equipment isn't as nimble as I'd like though it does have the body.  I ultimately went with a battery powered, a/c back up, amp that has current and is quiet, semi Home Made.  I have done some decent room treatment installation and modifications that have helped nicely as well.  Pre-dac-streamer is an Oppo Sonica with ModWright mod's and Jim McShane recommended tubes.  Very happy with the results. I can swap cables and components with my two systems and hear a difference each time.  

I did forget to mention in my post that system 2 is a Ps Audio Strata. 

It's pretty amazing for the cost, especially today, and I also hear the difference between cables with it.  Nice bass slam with it as well.  It does miss a little bit of staging & seduction but is hard to beat for an ALL In One and  it bested many super expensive systems at Axpona 2023 when paired with ProAc 3.8's. 

I  agree with @vthokie83 (above).  It sounds like the most immediate concern might be the lack of a dedicated, wired streamer. You should be able to get a very good streamer for well under $5K. Even a Bluesound Node, or a Holo Red (if you can get it), might be a good upgrade for less than $1K USD.  Try that and see if you aren't more satisfied with the speakers and integrated amp you already have.

Pair of used 92.5 dB sensitivity JM Lab/Focal Mezzo Utopia's and a pair of Jeff Rowland Model 12 Monoblocks(if you can find a pair!).

Speakers will be at 4 ohms Impedance and amps at 350W @ 4 ohms. 

I seriously doubt you'll be able to beat that combination. 

I use the H360 and i am keeping it.  With a room that big, I would agree that the JBL's will fill that room and then some.  But you should go listen to them first.  Nobo dy here can guess what sounds the best to you.