@roddyboy,
To my ears, the digital files sounded dull and flat with C2500 internal DAC. My source was Aurender N10. IMO, C2500 has a very nice Analog sound. If you hadn’t already done so, try some Telefunken NOS tubes.
If you really like the ‘house’ sound and synergy of MB100 through C2500, look for a used one. There is one on Agon on for $3500.
https://www.audiogon.com/listings/lis8e5f4-mcintosh-mb-100-music-server-streamerr-media-servers?crea...=
Outside MAC, like Matt recommended, Aurender N100C or N100H is a very good option but I recommend a better DAC to pair with Aurender.
Honestly, you’re are very unlikely to hear any difference between N100 or Google Chromecast as a digital source with C2500 internal DAC.