As a brief summary we can say: do not put your fingers from this receiver and get a little better (eg Yamaha RXV577).
But now to my experiences with this receiver. Delivery by Amazon went smoothly here. Connecting and setting up the receiver worked thanks to the very good assistant without problems. After that I have been playing first the current firmware. Then I have a Sony Blu-ray player and a Telekom Entertain receiver connected via HDMI. The Denon was joined by about 5 meters long high-quality HDMI cable to the projector. When connecting the Blu-Ray player to the normal (non-4K connections) it can last from 5 minutes to the HDMI handshake clean sits and an image can be seen. I then plugged the two playback devices to the two existing 4K HDMI ports. Here comes the image immediately. Once a Blu-Ray is inlaying the picture but disappears and there is only then when the Blu-ray menu. After the start of the film it takes then so until about 30 seconds to a picture. Now I have tried several shorter, longer, cheaper, more expensive HDMI cable. All with the same result. It could therefore be the Denon or at BenQ. I then first the BenQ replaced by Acer H6520BD. Here the HDMI handshake was a lot better, but unfortunately still not perfect. KO criterion was here, however, that no 3D output through the projector was possible in an interconnected Denon. I have then ordered the Yamaha and while waiting tested nor the other relevant features for me.
Spotify Connect unfortunately could never be into operation (Iphone, Ipad etc did not really want to the receiver).
With Air-Play connection always crashed after about 3-4 songs.
The sound was decent after calibration and let nothing to be desired.
Nevertheless, I have returned to this receiver due to the recognized limitations for me.
(Shortly: When Yamaha I have none of the problems)