OP, I too own 509x and am on similar path....fighting upgrade-itis. I can tell you I demo'd multiple speakers on my 509 before I brought it home, and the Sopra was the runaway winner for me. Paradigm Persona a reasonably close second. Oddly I didn't care for Kanta nearly as much. Magico was (IMHO) way to muddied, which I attribute to the 86db (from memory) sensitivity. IIRC Dyn is down there also, contributing to the lower volume problem you identify. Good luck and do keep us posted.
Dynaudio Confidence 30 vs. Focal Sopra 2
Considering an upgrade. Cost is similar. I'm running a Luxman L-509x amp and Cardas clear cabling. CD/dac is Luxman D-03x. My current speakers are 60i Dyns. They're great but I'm not in love. Could also consider the 802 D3 B&W but my dealer doesn't carry those and I want to work a trade. Looking for clarity. I want a piano to sound like a piano and violin to sound like it is made of wood. The 60i Dyns are great for Metallica, but I think there are better performers for classical. Thank you for your thoughts.