Meaning of separates is broad, but the core idea is to use separate processor and separate multichamp. You can also separate music from movies using either dedicated amp or dedicated amp/preamp for mains with theater bypass.
I moved, and re-did the speaker configuration using Audessy in my new home. The crossover was set to 80 mhz, but the speaker size was set to small. I can’t see much more detail than that, but I wonder if that’s why it would under-drive the speaker.
Technically, you’re not under-driving or over-driving speaker, but practically, read my prior note about Dennon AVR units. As a service man and techie I told that these units are unpredictable, overly sophisticated and absolutely unmanageable and unserviceable (anyone tries to ask me fix their Denon AVR, I simply send them away to whoever has another technical opinion about them). Your unit most-likely fails at some point and destroys your precious speakers. The point is you never will know the exact reason when dealing with it. If you try to make warranty claim and succeed, it will be a very good time to sell it right after you’ve been granted either overhaul or complete replacement of unit.
I stick to Sunfire products as they’ve presented to me maximum neutrality, precision and the most objective and truthful reproduction of instrument and voices with sufficient dynamic headroom. There are people that love Anthem products, but I find Sunfire giving more for the value.