I'm a past owner of a Marantz 2325 which was best dam stereo receiver I ever had! I wish it never got stolen from our house years ago...
Anyway, here's my two cents, but I think you need to match your "mid range stuff" and save your money for more impactful speakers later on when you can afford to go top end for the whole system. Or better yet save some $$ to get a better Sub as you may find the Sub-10 wanting after the Cerwin Vega S-2s.
Your Klipsch Synergy System F-2 have a sensitivity of 96 dB and therefore won't need gobs of power to drive them to reasonable (and even painful) levels. You said "Last year I updated my TV to a LG 4K 55" OLED (friggin awesome) but using my Box store Denon entry level receiver to check out my new speakers." didn't give much info on what is lacking on the "Box store Denon entry level receiver ".
Please advise what the Denon Model number is. Also advise what source material you want to listen to (BluRay, DVDs, Streaming, Sirius, Cds, etc.) and what percentage is Movies and Music. Can you also advise what input devices (model numbers are helpful for all) and the size (layout?) of the room / primary listening position?
If you are into saving $$ check out this site:
https://www.accessories4less.com/
Lots of folks here have gotten good deals there and are happy campers. Marantz and Denon are now in the same stable.