Separate Amp for AV receiver

And if you were actually prepared for that kind of a main speaker upgrade, they would def need their own outboard amp, like a 3ch cinenova high current able to control that trio.

Safe And Sound offers the 60xt mains refurbished not bad deal

I would consider the little MLs, the ESLX. I have seven Mains and surrounds, 2 subs, but only one working for now. I may mess around with it tomorrow.

With all this said we haven’t really address ur expectations as to SPL. I usually listen between 75-85db. If me and my son watch a real knock down bang up movie like Transformers or Tenet i’ll open up to 85-90db.
its not only important to match speaker timbre but establish what you want it to do sound wise. Are you interested in a ATMOS setup at all, the 4300 is very capable, i use mine as a quasi preamp processor. I use four amplifier channels for atmos and my Atmos speakers are little SVS bookshelf speakers, they blend pretty well

What is your room layout, is it sealed off like a dedicated space or part of the living space like a living room, familyroom, some people believe the two are different Lol