If you’re able to keep it and sell it in a week if you don’t like it, just give it a shot and see what you think...
I’ve owned the MRX720 and currently own the AVM 60 with Monolith 7 amp. I have never found that the sound quality of the Anthem processors can compete with the Luxman 2 channel system I have.
I have done 2 channel room EQ with ARC (both the old program and the new ARC Genesis) and found for 2 channel, ARC-EQ’d music sounded pretty sterile and lifeless. However it did do a great job of cleaning up the bass/subwoofer.
Give it a shot, if you have nothing to lose... try limiting the EQ to 200Hz or below and compare it to running EQ across the whole system. Also try out running the L/R pre outs of the 1120 to the Parasound amps and see what you think.
BTW, if you have anything invested in a digital front end (DAC) you’re going to be re-digitizing everything in the Anthem, rendering any benefit you may feel your current DAC is giving you irrelevant.
EDIT to note, this is not to say Anthem Room Correction and the overall sound quality may not be vastly improved on the STR integrated or separates; my experience is strictly with the AVR/pre/pro lines.