sending signal wireless from Mac to DAC- whats the best way ?

What he said.

Pick up a used node 2i. You can pick them up for 200 to $250.

A Node 3 can be found for ~$100 more.

You can airplay to them and connect to your DAC via coax.

While your at it, you can stream Internet radio for free and get trial versions of Tidal or Qobuz so you can hear and enjoy streaming. The nodes are controlled by your MAC (or your phone), but they do all the streaming, eliminating the need to send music from the Mac and freeing up your Mac.

AirPort Express, gen 3 Apple TV, WiiM mini or WiiM pro will all work.

thank you guys all for the valuable inputs. 

After long consideration I decided to rip the wall and run in wall cable. it will be way cheaper and more stable than any airplay.

Thanks !

ssg308

I decided to rip the wall and run in wall cable.

You won't be sorry. Nothing is better than a good hardwire connection, imo.