spend on the streamer or on the DAC ?

I have the Schitt Yggrasil and a PS Audio Direct Stream w/ bridge 2 in two different systems. They are both excellent DAC’s.  I slightly prefer the PS Direct Stream DAC, but that may just be the system, with my ears and preferences.  When I listen to the Yiggrasil, I don’t miss anything or wish it was something else - it’s that good. 
You could probably get a gently used PS DS for $3,500 to $4,000. 
The guys and gals at PS Audio and Schitt are very good people to work with. 
Some of the other DAC’s recommended here are also solid choices too. Good luck in your search. 

Given your budget +1 Lumin streamer/DAC (and add Sbooster) Check them out +1 on the PS Direct Stream DAC.

Maybe Mytek Brooklyn Bridge Streaming DAC too.

A few weeks ago I upgraded my Sonos streamer to a Auralic Aries G2, there is no comparison in sound quality. (Auralic Vega dac with Tidal, Roon).

@joeeuro

not at all a surprise

stock sonos streamer is a jittery source... needs reclocking

hence the w4s or other mod or appendage which solidifies the clock timing of the digital out

with this, i don't think you will hear any meaningful difference to other dedicated streamers

DAC - Audio Mirror Tubadour III is good, Audio Mirror Tubadour III SE is better