It’s no surprise that good stereo amp/gear could sound better than AVRs, even expensive ones. I have a couple of old Technics stereo Class A amps, and I find them too bright. Much lower quality than my AVR.I have the previous incarnation in the X6200. Although a brilliant receiver for film and TV I found it poor at stereo music. Several months ago I introduced a Rega Elicit-R that has HT by-pass into the system and that has greatly improved the overall presentation from the front left and right speakers. The biggest advantage is that I now no longer listen to stereo music through the Denon and the Rega has really shown just how good my speakers are. With surround music the Rega has certainly widened the front soundstage.
For stereo music I'm using a Marantz 8005 SACD player and for surround SACD a Pioneer LX-58 player. I know I shouldn't admit this on a Quad forum but I much prefer good old fashioned stereo.
In my case, I’m incredibly satisfied with the Denon 6400. I think it pairs well with the Monitor Audio Silver 8. Overall presentation, soundstage, dynamics, etc. are great in my tiny listening room. I have auditioned a few hi-fi systems here in Melbourne, and I have to say I don’t feel the need to upgrade at this stage. Perhaps I’m used to how my system sounds and I seriously enjoy it.
I’m also used to the sound of the Chord Mojo, either paired with Westone W60 or Senn HD600. In both cases, the sound is slightly darker than Denon with MA Silver 8, but equally detailed.
I’ve been using AVRs for a few years only, but for me there is no way back to a stereo system. I wouldn’t mind a second system, but I don’t have the space for it, nor the budget!