I can help I own the 228be (picture under my profile) and have owned Focal Chorus speakers and currently use Marantz receivers in my home theater (highpassed through my two channel).
-your marantz will drive the Revels with easy. They are very easy to drive but are a 4 ohm load. The Marantz PM- 11S3 doubles down at 4 ohms and should be super stable. If your interested I am happy to hook up the speakers directly to my old Marantz receiver (SR5005) and tell you want I think. It is not near as good as the PM-11S3 and has had no problem driving even some tough loads like Thiels I have had on it for a short time (on the wife’s TV…)
-I am amazed at how loud the revels can play. I mean obscenely loud I was hitting 100+db peaks today and don’t think my meters ever went above 4.5 watts. They sound so clean all the time no matter how loud they are played. No since of compression of any kind.
-as for playing quite, they are fine but nothing special. Tonally they stay the same but I feel like the soundstage starts to open up at 75db and by 85db has spanned the room. I kind of feel this way about ever cone in a box speaker though…
-revel vs your current Focals? It will be a huge upgrade in every way. 228be vs the Sopra well it will be pretty close. At the same cost I like the Sopra’s better but they are a lot more money. They are very close but I feel there is a bit more texture in the upper bass with the Sopra’s and maybe a hair sweeter mids. But the Revel’s mid are very transparent and natural. Focal is tuned a bit more maybe and Revel is a bit more just the facts.
-down side of the Revel 228be (and also tue sopra) is they lack bass extension. They have both given up bass extension for efficiency. I feel like both speakers need subs but I think everything needs subs lol.
-as for pairing I use McIntosh gear on the revels and I enjoy it. Takes just a bit of edge off and sweetens them a hair compared to my class-D amps. I feel like marantz is McIntosh’s long lost brother with a similar sound so it should be a good paring.