So, lemme see if I got this right.... you are streaming a service from some device (iPhone, iPad, laptop??) to the Chromecast via Bluetooth (strike 1), then the Chromecast is connected to your Gumby via USB (strike 2). Now onto Redbook CDs - you are playing them thru some CD transport, outputting SPDIF (hopefully coax) to the Gumby.
If I got the above right, there is no doubt in my mind that Redbook would be superior to your streaming services (any of them).
I finally got amazing "streaming" music quality once I took USB out of the direct loop using a DDC (in my case a Matrix SPDIF2, converting USB from my MacBook Pro laptop to AES/EBU for my DAC; even SPDIF coax sounded superior, but I like AES/EBU a little better).
I don't think any streaming service will outperform Redbook in your setup, assuming I understand your setup correctly.
If I got the above right, there is no doubt in my mind that Redbook would be superior to your streaming services (any of them).
I finally got amazing "streaming" music quality once I took USB out of the direct loop using a DDC (in my case a Matrix SPDIF2, converting USB from my MacBook Pro laptop to AES/EBU for my DAC; even SPDIF coax sounded superior, but I like AES/EBU a little better).
I don't think any streaming service will outperform Redbook in your setup, assuming I understand your setup correctly.