spend on the streamer or on the DAC ?

I have stream from Chromcast audio digital out bluesound node 2i digital out cocktail Audio X45 digital out Allo digi signature USB out and more streamers to my Preamp DAC Michi P5 zero difference
analog out is different story
like others said the interface of streamer APP is more important to me that’s why I’m using Naim Atom Uniti as a streamer only to my preamp the interface of Naim app is amazing compare to Cambridge 851 app auralic G1 app Bluesound app

If I had to choose I'd spend the money on. DAC.
However, with your budget, maybe consider a Lumin streamer/DAC.

To me it can make sense to combine streamer, DAC, and preamp in a single box (then just add a power amp and speakers ... or active speakers).  That way you're paying for just one chassis and you reduce the number of interconnects.  This "integrated preamp" is a modern, digital alternative to the traditional integrated amp.  Many products are available that combine 2 or 3 of these functions. Prices range from ~$500 for Bluesound to nearly $40K for the T+A SDV 3100 HV.  

I have owned the BS Node 2i, the iFi Pro iDSD, an ultraRendu (streamer/NAA only, no DAC/preamp), and the Matrix Element X. Lately I've settled on the Matrix Element X, which has an excellent DAC, WiFi/ethernet streaming, decent input switching functions, and very good volume control. As far as I'm concerned, all these devices perform the ethernet streaming function about equally well (all else being equal, or nearly so).  As for the DAC per se, I'd find it challenging to isolate the contribution it alone makes. FWIW, in ASR testing, many devices (including the Element X) have measured better than the Node 2i.
https://www.audiosciencereview.com/forum/index.php?pages/Audio_DAC_Performance_Index/

In this setup my Node2 does the full MQA unfolding before sending it to the DAC (via digital coax).

Actually, no.  You only get the full unfold if you send output to the analog outs of the Node 2.

https://support1.bluesound.com/hc/en-us/community/posts/360037876633-MQA-Confusion

I have yet to see a technical reason as to why the streamer does or doesn't matter, but my experience was that an external DAC did improve sound quality (in my case an Auralic Vega), but that replacing the Node 2 with a higher end streamer/DAC (for me it was the TEAC NT-505) resulted in a greater improvement in sound quality, a less "digital" sound, and a larger more "holographic" soundstage.  As others have said, the app you use to control your streaming is also important.

One point that seems to be getting lost in the conversation is how your streamer is connected to the internet. I noticed a huge difference in all aspects of the sound after I ran a direct wired connection to my streamer. Wireless is convenient but igo with the direct connection when ever you can. I also added an IFi filter on the connection and it cleaned up the jitter and noise.