spend on the streamer or on the DAC ?

I recently purchased a naim 5 xs for my office system, (Focal Utopia, Flicks Euphoria, Audioquest Vodka) streamed direct from a dedicated modem. I also have a two channel system in a dedicated listening room. I have been so impressed with the naim unit, I exchanged it with my Lumin D2 on my two channel system. For my listening preferences, the naim easily outperforms the Lumin. A pretty good comparison, same system, same environment. The Lumin is very nice, but entry level, you may have a better experience with a higher end Lumin. I would also add, I prefer the naim interface. Many of the negatives you hear about the Lumin connectivity and less than ideal app. I have experienced.

I tend to go with the DAC because if you hear a composition you find so beautiful you might want to download it into your library and get it in high resolution it will sound better than what you can stream. If you run into unexpected financial ruin and you have to give up streaming subscriptions you get to keep your DAC and the rest of your system.

concur that sonos streamer, with a w4s digital reclocker upgrade (or outboard reclocker) is an excellent sounding source... delivers spdif at 96k

plus using the sonos software is easy peasy 

this and the bluesound node 2i are excellent cost effective streamers that make no apologies to more expensive ones, unless you want other forms of output like i2s...

agree the Wyred 4 Sound Sonos is a huge improvement over the standard Sonos...currently using mine into the Marantz Ruby K1 DAC section...sounds great 

In my personal experience, if the streamer doesn't apply badly implemented sample rate conversion or otherwise messes up the signal (even cheap solutions like chromecast audio are in this category, the chromecast hdmi and most android based solutions are not), then the spdif signal from the streamer only requires jitter to be reduced before reaching the dac, since most dacs are very sensitive to incoming jitter regardless of marketing bs or technical descriptions of nice concepts that are not properly implemented to be effective at the low levels advertized which requires not only clocks but also ps and routing. Most dacs starting at a few hundred dollars can sound great if incoming jitter is under control. Often the simpler the better, ideally without incoming signal treatment like src.
Before changing the streamer or the dac, my advice would be to test a jitter reducing device between them with as good as possible digital cable before the dac, so that the best of what the existing units can do can be assessed. I tried several  solutions over the last decade and only 2 really stand out: SynchroMesh asrc reclocker for SPDIF from Empirical Audio with reference coax cable and AFI USB synchronous reclocker from Acousence. 2 totally different technical solutions but both exceptionnally well implemented and effective. My bet is you will not believe what your existing setup can actually deliver. Try to get a money back guarantee or a possibility to audition, as usual, since the rest of the playback chain must be up to the task as well... especially the speakers and their interaction with the room.All the best in your audio journey, Patrick