spend on the streamer or on the DAC ?

Source is important but the DAC is the larger determinant of sound quality.  I use a Bryston DAC3 which has 4 HDMI inputs.  My Oppo player can output the DSD layer of SACD via the HDMI perhaps your Mac can do the same?

My local dealer, who puts together some very expensive systems, usually recommends the Sonos or Roon streamer.  It is not uncommon for his customers to have Sonos feeding an Audio Note DAC5; now THAT is a massive price discrepancy.

I have a different view than the others.  Yes, the DAC is very important, but I also found that the streamer or source is as important. 

I started with a Node 2 going into an outboard DAC, and found a sizable improvement in performance when upgrading the streamer going into the same DAC.  BTW - It didn’t present itself as a tonal difference, but In the form of a lot more spatial detail.  The Node 2 sounded “flat” dimensionally in comparison. The upgraded streamer also offered more information and musical detail but the most obvious difference was how the soundscape just opened up dramatically.  

Perhaps you could audition better sources along with better DACs to see how it works in your system. In any case, YMMV but it’s worth exploring.

My $.02.