spend on the streamer or on the DAC ?

The DAC is more important, not the price.
Get the Yggy in your room with some highly regarded cheaper ones and you might surprise yourself. The secret is to find the one you like.
Cables, power supplies and ethernet quality usually make more diff in SQ between streamers than brand.

DAC  but a very good one does not have to cost a fortune. 

The dac is the sourse or the voice of the system , the streamer 
is the delivery to the dac.

I'm in the Dac camp but also make sure your streamer whatever it is has a good power supply. I've used an Auralic Aries Mini for 5 years now into two different Dacs. The one big improvement to the streamer itself was adding the Sbooster power supply.

I’ve got the Node2. There is no difference in sound quality between it and the 2i. For its price point the DAC in the Node2 is fine. It was a big jump recently adding an MHDT Tube Orchid (tube is on analog stage) DAC. I like having the streamer and DAC separate anyway. In this setup my Node2 does the full MQA unfolding before sending it to the DAC (via digital coax). Just changing the tube on the DAC changes the sound dramatically. I couldn’t be happier with the setup I have now.