I think most would agree (as I started saying..
),on money/budget no object basis, prepro is the way to go. In that case, like ADTG suggested, a separate prepro may be even better, but I would research it to the nth degree before jumping in just for the "separate" thing. For example, you can spend a lot more on the so called boutique brand, only to find later they actually used lower grade components such the the highly important (for those who believe) DAC, preamp/volume control ICs, among others. When I say "research", I don't mean the subjective part of professional reviews, those are highly subjective, often borderline on exaggerated bs.. I mean specs, parts used, evidence of good build quality (not lead plates..),bench tests etc.
On the practical side, the picture is very different, because factually speaking, there no hardly any evidence something like an AV8805 would, or could result in one's speakers sounding any different, let alone "better" side from people express their opinions and audition experience that are highly subjective and varies a lot, by nature. That's the reason why I switched back from AVP to AVR, after spending more and gain nothing other than bragging right. So for better values, imo the x8500h is actually a good deal if 13 channel is a must. If 11 channels is acceptable then there are much more choices.
Edit: To Op, I should mention that the Denon has an significant advantage in having a close to real preamp mode. That would avoid some undesirable scenario such as the one Gene noted on the SR8012:
https://www.audioholics.com/av-receiver-reviews/marantz-sr8012-receiver/marantz-sr8012-bench-tests
I was unable to do a preamp frequency sweep exceeding 1.2Vrms as it tripped the protection circuits since the power amps were still engaged and exceeded full rated power (140 watt/ch, 8 ohms, Av = 29dB). Unfortunately, Marantz doesn't offer a preamp only mode to disconnect the power amp from the circuit if you're using only external amplification.
I don't recall him finding something similar in the older Marantz and Denon AVRs AH reviewed in the past, so this may be something new, or an anomaly that Marantz could fix in a future FW update. If not, I would avoid using Marantz AVRs as prepro with amps with lower to average gains such as ATI's, because a 200 W ATI would need 1.6 V input to reach their rated output.
