7.1.4 receiver/amp help

[Atomic4877]

I am currently in the process of moving from a 5.1.4 setup to a 7.1.4 system. I had a question on which channels I off my av receiver (Denon X6500H) and which channels I should run off my external amplifier (Emotiva A-5175). Currently in my 5.1.4 system I have my front left, right and center channels running out of the Emotiva and the remainder (left/right surround and 4 height atmos channels) running out of my X6500H. I currently have following speakers Klipsch RP-8000F for L/R, Rp-504C for Center channel, RP-5000M for rear surrounds and the RP-500SA’s for my front and rear height channels. I am adding the RP-502S for my side surrounds. I am torn between whether it would be better to run the new RP-502S off the external amp and thus using all 5 channels on it, or to run them off the X6500H which would be running 8 total speakers at that point. I was not sure if it would be best to leave most power running to the L/C/R channels by only running 3 channels, or to run them off the Emotiva and freeing up some headroom for the Denon.