50’ Connection Between Mac and DAC

I’m currently wirelessly streaming CD rez AIFF files from iTunes on a 2017 iMac to my main system (2 rooms away) using an older Airport Express device. I want to go with a wired connection from the Mac to a DAC (Looking at the Schiit Bifrost 2 or, less likely, a Chord Qutest.) which will reside in the rack with the main system......I really don’t want to purchase a dedicated streamer at this point. My understanding is that connection runs of this length are best done with something called SPDIF coax (??). Can this be divided up in such a way that I could use 3 runs of this coax - one from the Mac to an adjacent wall plate, an attic run, and then a third run from a wall plate adjacent to the main system to the DAC? If this is possible, would it be a significant SQ improvement over what I’m using now?

Hi OP:

The pi acts as a receiver/converter.  It will take what your mac sends and output via USB.

Your Mac will need to be on and on the network to serve as the Roon server
If you’re going to run 50 feet use AES3 it’s good up to about 100 meters. Get a Schiit Modius it will take AES3 input and balanced output. Get a USB to AES3 converter and place close to your computer try to make the 50 foot run with one cable. 

You can: 1) Connect the mac mini to your wireless  router with an ethernet cable 2) Connect the Raspberry P i to the wireless router with an ethernet cable 3) Connect the Raspberry Pi to the Schiit Bifrost 2 with a USB cable. 4) Install ropieeexl  on the Raspberry PI 5) on the mac mini install Roon server or Audirvana
I tried this.
Waste of time.
Did not work.
It would probably sound like rubbish if it did.
Settled on line out from Schitt DAC and a RF remote to control the computer.
Then I grew up.

For what you gotta spend on a decent balanced cable and interfaces you will get better SQ AND control with a streamer.
Are you currently using the internal DAC in the Airport Express? If so, just stick with your wireless setup and get a decent DAC. You can use the optical out of the Airport Express into a DAC. It will give you the biggest improvement in SQ. 
My setup is similar to your setup with loseless ripped CDs on a Mac Mini. When I compared my wireless setup to a wired setup, it was either hard to tell any difference or the wireless sounded better, depending on the cabling that I used.