With noise it is easy to tell/predict even just going by the published specs, and definitely by measurements. One just have to stick ones' ears (could be risky though so need to be careful) to within a few mm of each driver of the speaker, hear and compare...
One thing I bet not well known is that the recent Denon AVR's including my 2017 AVR-X4400H have very quiet preamp/dac even when compared to some or many AVPs and pure preamps. I just experimented this recently, using a RCA to XLR interconnect with my very quiet Hypex and Purifi amps, and found the AVR was much quieter than my AV8801(that has extensive shielding based on the marketing information), and about as quiet as my $2,000 Cambridge Audio preamp, despite the prepro and the preamp's balanced I/O advantage. That's why I caution that preamps, even the real ones without build in dac and dsp functions do not out perform some good AVRs. It seems your findings are consistent as mine.