I’ve recently added a Chromecast audio to the hdmi of my Denon AVR amp, with TV, DVD and CD all routed through it – even an ipod classic…

I’m streaming Spotify to it, using the high quality setting on the spotify app, but the sound is nowhere near as good as I’d expect. Listening on bluetooth headphones is more appealing than through the speakers (an old set of B&W 603s). I’m not expecting a top-notch high-end sound, just something a bit better.

Is there anything I’m missing in terms of set up or are there better streaming options?

Have you enabled full dynamic range in the settings of the device via the google home app?

Like this…

https://support.google.com/chromecast/answer/6290498?hl=en-GB

Chromecast Audio uses either optical (mini TOSlink) or electrical 3.5mm connection, not HDMI (possible I’m not aware of an audio connection referred to as HDMI). Is that a typo, or are you using a TV Chromecast by mistake?

For what it’s worth, I found the optical link MUCH better on my stereo, although my cheapo portable speaker is fine with a normal 3.5mm lead.

For balance, I have two and tried them side by side. one optical , one analogue through my amp. The difference is barely perceivable to my ears. Although i do get crackles on the analogue input when there is no active cast. but that was improved by using shorter leads.