How much should I spend on a new DAC

Your biggest bottleneck is probably using the computer as your source, and adding a good streamer will make a huge improvement and probably more than upgrading your DAC.  That said, for around $3k you could add both this Innuos streamer and Gustard DAC and you’ll be in a whole new world of performance.  Also, ditch Tidal and give Qobuz a try. 
https://www.tweekgeek.com/pulsemini/

https://smile.amazon.com/Gustard-R26-Discrete-R2R-DAC/dp/B0BDLKRK65/ref=sr_1_3?crid=2IZRXCIMZZSJL&keywords=gustard+r26+dac&qid=1674179512&sprefix=Gustard%2Caps%2C200&sr=8-3

Just my $0.02 FWIW, and best of luck. 

@soix 

I understand the computer can be a weak link. But, even though if I add a good streamer I will still have to use the PC as a roon core. I don't think using a  LAN connection instead of USB will make such a big difference  

I agree that separate streamer and dac would do you a lot of good. However I would put the brakes on the r2r recommendations for a dac. I had an Ares II and then bought a delta sigma Gustard X26 PRO and ended up selling the Ares II. No doubts that the Gustard offered a much better sound in my specific system. A Bluesound Node 130 connected to the Gustard would be a great start for about $2k. Then the upgrades start... Made quite a few myself but stuck with the Node and Gustard. Enjoy the trip.

I agree that the PC is a limiting factor and would get a streamer/DAC combo. HiFi Rose, NAD or Cocktail Audio come to mind,

Go audition streamers and DACs. Only you can decide what would be best for you. Not this forum. All you are going to get are opinions.