My intuition is telling me, you must be... French.
So far, you have to know that the M500 is (quite probably) a State of the Art DAC for the price, with specs at 117db SINAD. There is no way your Yamaha comes close to this level of transparency. A DAC of this level is IMHO overkill for your integrated. You could better look at cheaper alternatives, like Topping DX3 Pro or D50s, even a Khadas Tone Board with case (also sold by Audiophonics).
About the Chromecast Audio, its optical performance is terrible stock, unless you're using Tidal with Roon:
https://audiosciencereview.com/foru...ents-of-chromecast-audio-digital-output.4544/
Quite more expensive, less powerful under 8ohms, and I doubt it performs "that" better than the Yam distortion-wise.