Digital File Playing

It helps if you specify a budget, before someone recommends a 20,000 dollar device to solve your problems.
Otherwise, I am not sure I understand your request.  I have played files both from a Windows PC and Macs into a DAC and once you have loaded the proper drivers usually required for a Windows PC they don't sound very dissimilar.  There are software programs for computers that enhance music playback, some have both Windows and Mac versions and some don't, but you can obtain excellent results with either.
Having said that, most people here prefer dedicated streaming devices, because they eliminate a lot of the PC type issues and look and feel more like audio components.  
  There are the things required 1) A source of files--some type of HD that CDs have been ripped to. 2) A player that sends those files to the a DAC. 3) the DAC
  The simplest are the all in one devices, such as the Bluesound Vault2, which rips and stores the CDs on a HD and comes with a DAC.  Other companies that are somewhat higher end are Aurender and Innuous (sp?).  
Again, define a budget and you will get better help...

Thanks, budget, $500-1000.
I have the flacs and can rip with no issue.
I don't want to play the files from my PC directly, rather from a box away from my PC into an external DAC.

What I am looking for is a sort of network bridge like Sonore microRendu, but that is perhaps halfway answering my own question.

Sounds like you want a server located elsewhere from the PC, but will it be close enough to the DAC to do a wired connection or will you do WiFi?

You could get a Dac  with a USB input that you could just plug an external harddrive into that would be the easiest route.

Player choices are also limited by DAC input. USB, SPDIF, i2s?
You don’t need a server just put the files on a SSD and plug it in.
BTW microRendu doesn't even have a USB input. Neither I nor SGC could get it to play any local files. REFUND.
I have 5 different streamers in your price range that all play local files.
I do mean DIFFERENT.