The thing that I like about the CA Azur 550A is that it has no dac or any internal components or electronics, so that it gives a cleaner signal.
I can choose the DAC and upgrade it appropriately, since technology in this context has improved in the last 10 years - but in terms of how an A/B Amplifier works? It's stayed the same.
The argument that people make is that AVRS have way more components that can colour the signal, compared to a 2 channel amp.
Cleaner signal than what and how do you measure "clean"? Wouldn't clean imply low distortions and noise?
According to specs, and/or measurements:
Azur 550A:
0.05% 20-20 kHz, at 80% rated output, ie 48 W
0.02% at 10 W
AVR-X4700H:
0.005% 20-20 kHz
Measurements:
0.0022% at 80% rated output
0.0025% at 20% rated output
I have compared my Cambridge Audio preamp that has lower distortions than the integrated amps, with an AVR-X3400H, heard no difference, took some measurements with REW the found there is no difference in frequency response either.
If an AVR, such as those measured by Amir colors the sound it would have been shown in his measurements. So far I don't recall seeing any of the Denon, Marantz, or Yamaha's would color the sound to the point it would be easily identified audibly.