Denon AVR line has a 'pure direct' mode where it supposedly shuts off the internal amps completely and sends a 'pure' signal from amps to speakers...so that's what I use in 2 channel listening...but I am suspicious of it still bottlenecking as you describe
Yeah, you’re very right to be suspicious. The problem is the sensitive and relatively low-level line signal is still going through the cheap preamp electronics of the AVR, which is the heart of the problem. Think about how much you paid for the Denon — how much do you think they spent on the stereo preamp section in it? AVRs are designed to hit very aggressive price points in an uber-competitive market, and the first thing to get sacrificed is parts quality (think critical/expensive parts like power supply, capacitors, etc.) and is why they’re so compromised from the get go. Do not minimize the importance of the preamp, and at the very least I’d encourage you to try a good stereo pre in your system just to hear for yourself what you may be missing. Lots of places offer trial periods these days, or you could buy something used at a nice discount and that minimizes your risk if it doesn’t work out. Sorry to be so wordy, but this is really important so thought it was worth going into a little more detail.