Can I use my SSP's DAC instead of external DAC with Mac Mini?

I have a MacMini running Roon with a 2TB external drive containing my library of about 25K songs. About 3K of those are iTunes downloads and the remainder are songs ripped from CDs into 16 bit / 44.1 kHz AIFF (lossless, compressionless) format. Also have a few hundred high-res music tracks. I am delighted with the sound and performance of the MacMini as a music server. I use an LH Labs DAC fed via USB to feed my Rotel preamp. The Mini sits on my Audio Rack next to my DAC.

I must be lucky. The MacMini runs very quiet and my old ears do not perceive the "noise" added to audio by the Mac OS's multiple processes running. There are some who believe the music server/computer should be dedicated to just one purpose: audio and also insist the server/computer should be located in another room/closet. 

I also use the MacMini as a video streaming computer to a 65" TV via HDMI . I use an Apple wireless keyboard and Magic Mouse to control things and stream Netflix, HBO Now, Hulu, PBS, and YouTube as well. So my preference for the Mini also has to do with it doing double duty. There's a lot to be said as well for internet surfing on the big screen with a group of people. Many control options available for iOS devices. Great two channel audio too. (Keep in mind that the video streaming can just as easily be done with an Apple TV, Amazon Fire Stick, Google Chromecast, or Roku device - these are much much cheaper.)

There's a lot to be considered when deciding on a music server and now is a good time to be doing that as many products are available. I love my Roon subscription and the convenience of controlling it remotely from an iPhone/iPad. Roon is also an excellent multi-room system where each endpoint can be grouped for the same audio or controlled separately and each playing different tracks from the library. 

Good luck. 

DBTom2 - Rotel is a sister brand to Classe & B&W -  we're chasing similar goals. I just added the 65" OLED from LG (E6P) so it surfs the net with its own kludgey OS. I plan to connect HDMI from Mini to TV, as a monitor as / when I need monitor for Mini, but don't plan to use it that way much. Mostly the Mini is for remote music playback using Apple devices as a DJ/remote.  

Why not purchase a USB to SPDIF converter. many come up used here on AG.  A original Music Fidelity V-Link (black version) would work for your application. This might best be found on E-Bay. 

Mesch - operating under the "fewer devices and connections is better" premise - straight cable is fewest # of points to introduce possibility of degradation. Not being cheap, being careful.

" Mesch - operating under the "fewer devices and connections is better" premise - straight cable is fewest # of points to introduce possibility of degradation. Not being cheap, being careful."

That's only true up to a certain point. Your system isn't at a level where a usb to spdif converter will have any real audible negative effects. If it using one helps get your system setup the way you need it, just use one. Besides, if the "fewer devices" rule was always true, we would all be listening to integrated amps with built in dacs.

" DBTom2 - Rotel is a sister brand to Classe & B&W -  we're chasing similar goals."

Classe was bought by Rotel/B&W a few years back. The 2 brands are very different. Ownership is about the only thing they have in common.

" mb1audio02 - I see that some of the higher-end cable-makers (Wireworld for example) sell a cord with mini-optical to toslink ... I actually haven't bought the mini yet - wanted to make sure I could make it work first."

You don't need to get an expensive optical to toslink adapter. It doesn't do anything. Its a mini jack with a hole in the center for the fiber optic light to pass through. 

" Mostly the Mini is for remote music playback using Apple devices as a DJ/remote.  "

Try a free music player called Clementine. Its better than iTunes and supports FLAC. Remote app is available for iOS and Android. Everyone who tries it, keeps it.