After exhausting myself researching the length and breadth of hardware and OS choices for a music server (not to mention the hard care audiophile upgrades and tweaks), I'm thinking the best way to get my feet wet is to buy a refurbished SFF pc of about 2015 vintage, remove the DVD drive, install MC and connect it to my Outlaw 2160 receiver through USB. Prices are currently $150-200, with Win 10 installed.
I know there are cheaper options if I go with a Raspberry Pi, or use Linux, but though I've installed and used Linux before, I just don't have the time or patience right now to set it all up, though I will likely try out Daphile or Snakeoil at some point.
I also know that a PC like this is far, far from ideal in terms of noise (physical noise and electrical noise from fans, power supply, etc.) but what I like about this approach (aside from the fact that I'm a cheap lazy bastard) is that any upgrade I make to better hardware or a newer system, I can test against my middle-aged ears for myself.
If anyone thinks I'm wasting my money, or has suggestions for alternative cheap hardware, I'd be happy to hear!