Recommendations for digital music servers?

If you want to use the UPnP streaming function of the Hegel H390, then you need a UPnP server. Install MinimServer (v0.8 is free, v2 has free and paid options) on your Mac Mini, and connect both the Mac Mini and your H390 to your local network.

Thanks nekoaudio for the feedback, don't know about UPnP but I will research. I've mostly listened to analog so much to learn...

exaSound Delta Music Server A digital front end comprises several elements: data storage, library management, Grimm Audio MU1 music streamer.


Walgreenslistens

As @nekoaudio has indicated, your Mac can be used as a server.  Since you already own this, and are new to streaming, it’s the best and most economical starting point.  I used a MacAir for a while as a server Most servers are packaged with streamers and you already have one.The Mac also gives you the toslink option, and many servers limit you to usb.  As to which sounds better, use your own ears to decide.

  Eventually most of us move on to dedicated servers, and not have to put up with the issues that can arise with using general computers.  I recommend the Melco N100.  It is a server/streamer, and it comes with a 2TB HD.  Sounds great, works flawlessly.  You can transfer the contents of your MacMini to the HD or connect the Mac and just play.  It is usb only, however, so if you decide that the usb input of your DAC is subpar, then not for you unless you use a converter 

I’d consider an Innuos Zen Mini Mk3 with upgraded linear power supply.  It’s a little north of your budget (ain’t that always the way?) but is a very good and easy-to-use server and streamer (also a DAC you prob don’t need) with a coax digital out.  This could turn out to be a dual benefit as streamers matter and I’d bet the Innuos is a better sounding streamer than the one built into the Hegel — could be wrong tho.  Anyway, just another option.  Best of luck.