@fatrich
FWIW I 100% Agree with
@Mr Wolf
If you look at my signature, I'm using the same AVR & subs as you. My room is around 4ft longer than yours, but the same width. I use an Audiolab 6000A for 2 channel music (this also powers my front speakers in my HT setup as it has HT Bypass. The rest of my speakers are all currently powered by the Denon.
I do aim to get some multi channel power amps (most likely Emotiva Basx) in future. I'll then run all my speakers off the power amps (as you do). The ultimate goal or end game is to then replace the 4500 with a processor. Like you, I don't like the newer Arcams, but am interested in either the Anthems etc. It appears we are almost at a similar point in our "AV journeys" and as such imo I'd be inclined to save your money and put it towards one of the higher costing processors - with better Room EQ (ie Anthem, Lyngdorf Lexicon etc). This is exactly the route I'll be taking as for me there's little value in swapping a very good AVR, to a processor from the same brand which has the same Room EQ.
Edit: I'll also add. The suggestion earlier in the thread to replace your current AVR with a 3700, quite frankly begars belief, so I'm glad you dismissed it as a viable option!
(As Mr Wolf points out that most definitely will not add
any significant upgrade in SQ)