Best standalone music server?

The Sony Haps are great units, but only stream Spotify as far as I know.  Future services maybe in the works.  You might look into the Auralic Altair.  It's a DAC streamer and if you add an internal HDD or SDD it becomes a very versatile server.  You can also use it as a preamp connected directly to a power amp.  It sells for under $2K so would fit in your budget.  Good luck with your search.

Since you already have the cabling, you could get a Denon Heos link for $350 and run an ethernet cable from the router to Heos and then either analog or digital to you pre or DAC. Then get a Tidal subscription for $20/mo. Done.

If you search Tidal you may find most of your CDS are there. Heos has all the subscriptions, including Tidal, Tunein, Spotify, etc. Bluesound Node does too.

I've used an Oppo BD-103 with an external Western Digital hard drive tucked behind it. When I need to update new music, I attach the drive to my laptop for downloaded or ripped files. It doesn't eliminate the computer completely, but it is capable of network streaming so you could have a NAS drive in another room. As far as the equipment rack goes, the Oppo fits in nicely. It allows CD/DVD/Bluray playback, but could be used nicely in a music only system. It has great DACs already, which I use and feed via analogue RCAs into the back of my Denon 3802 receiver. It is used for both music and home theater and allows 7.1 decoding. However, for a music only system, and depending on budget, the Oppo 105 has better audio capabilities (and video if you want it). The Oppo can work as the media server, preamp, DAC and CD drive. One minor annoyance is that for gapless playback, you have to hit a menu button and select gapless for ripped files. If it would default to it, I would think this would be an ideal setup for minimizing various "boxes" in my audio rack. Just the Oppo and an amp would get the capability to play any audio disc and ripped files. I am looking to upgrade to Oppo's new UHD player in the near future, but from what I understand it does not offer Pandora, Tidal or other services built in, so the 103/105 would be better since they do have them. I've tried computer based with XBMC/Kodi, Plex and others and all were a PITA to set up correctly. Plex worked the best at the time, but it has been a while since I've tried any of them. I'm sure they've improved since then. 

So I thought I would at least give exact audio copy a try out on my pc, but after the results I am going to assume it is very dependant on age/speed of pc and drive etc as results were very poor tbh.
The very first cd i loaded ( polyester zeal by red sun rising) it did not find the metadata, however it was easy to edit and add myself.
Then it took 17 minutes to rip as wav files.
I did a compare with windows media player which not only found the metadata right away but ripped to same wav format in 7 minutes.
Files were ripped to the pc,s own internal hard drive, is it possible to get these fast EAC rip speeds it would need to be ripped to an external drive or is because my cranky old hp all in one is just too old and slow?

I listed to both versions through my tv which feeds via toslink into my esoteric into my arc into my bat and could not tell any difference.
Obviously this is less than state of the art but all I had to experiment with right now.

@uberwaltz I would very seriously recommend getting dbpoweramp or similar ripping software that will allow you to rip flac and not wav files. You will be grateful that you did wav files are very large relative to flac and to me at least sound identical.