Streaming Transport without DAC- few choices


I already have a very good DAC. I already have a very good preamp. There seems to be a dearth of streaming transports under $2000 which noes not include a DAC, does not include preamp function or does not include both. 
So tempted to just get a Mac mini and use that as a dedicated transport/server, played through audirvana 


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I’m very satisfied with the sound of the $800 Pro-ject Stream Box Ultra S2. It’s based on a Raspberry Pi with the power supplies and analog sections optimized for low noise. It certainly sounds better than a laptop or iPhone that I used for a short while. At some time if I get bored with time on my hands, I’ll compare it to more expensive streamer/transports to see if anything else sounds better. I'm thinking Innuos or Auralic. I’ve heard the Naim NDX 2 used to play back local files from a flash drive through my Pontus II DAC. It sounded good, but wasn’t noticeably better (at least without comparing head-to-head with my Pro-ject streamer).

You can plug a hard drive, solid state drive or flash drive into the Pro-ject streamer so it becomes a transport for local files.

The Innuos Zen Mini is supposed to be quite good as well.

In theory, a dedicated streamer will have less EMI and RFI than a Mac Mini or other general purpose computing device. Maybe buy a streamer used and see how it works for your needs?
The Innuos Zen Mini has a DAC, so I’d recommend its big brother the Zen Mk3 that’ll stream but also has onboard CD drive and storage so you can easily load all your CDs directly into it and have access to all your music through one device.  Anyway, that’s what I’d do FWIW, but best of luck with whatever you decide. 
I trialed a used Primare NP5 to good effect. Simple, small footprint, clean delivery.
Mac mini may sound purdy good. But dealing with all the patches/security upgrades is a headache. Go for a dedicated streamer. +1 on the Raspberry Pi. I found a Bryston BDP Pi used for $500 (basically a Raspberry Pi). Manic Moose interface is spartan at best but the SQ is excellent. You can get a SGC Sonic Transport and Micro Rendu for less than $2K. Run The Roons or BubbleUPnP.