spend on the streamer or on the DAC ?

Interesting to read this thread.
In the UK 'streamer' seems now to define a unit with both DAC and network bridge,
I demoed the following network bridge units in my own Vitus/Boenicke system. Hence all wen5 via usb to the Vitus DAC. 
1. Auralic Aries G2 (£4,000)
2. Pro-Ject Streambox S2 Ultra (£600)
3. SOtM-200 Ultra NEO SE (£1500)
4. (3) above with its own sPS-500SE power supply (total £2200)
5. (3) above with the power supply in (4) and a separate clock sCLK-OCX10 SE (total £5700)
To my ears there was no audible difference between (1) and (4).(5) was better, but not massively.
This may be DAC-dependent as it is my understanding that a good DAC, and the Vitus is a very good DAC, is less dependent on a good Network bridge.  But I am no engineer.

From previous DAC comparisons in my system I would say therefore that DACs define the sound a lot more than the network bridge (streamer). 
Personally I would not combine them into one unit.  From my evidence I would buy a network bridge, stick with it, then enjoy trying out and swapping in and out various DACs.

As an aside, and in case you don’t have one in your set up, I would recommend installing a switch between your router and Hi-Fi and run cat8 cable between all units.  This made far more difference to the sound than any difference between network bridges. And a bigger improvement than between many DACs. 

Here’s my opinion.

Using your current system and how my system evolved I would suggest a DAC.

My current sources are a Turntable, tape deck, DAC with Streamer (Moon 280D) into a McIntosh C2600 tube preamp and MC 302 amp and Sonus Faber Sonetto speakers.  I used to think the speakers were the most important and based on upgrading from a NAD C375 with Sonus Faber Venere 3.0 with the Turntable and tape deck using the Node 2i as a DAC/Streamer.  I will admit I believe the source is the most important. 

I then upgraded my DAC and speakers - using a Moon 280D with built in Mind2. While I know Roon has great functionality I am find using in Moon 280D having it connected to my personal server for my digital music as well as linked into my TIDAL account.

Additionally your DAC can support your CD transport.  

I have Teac NT505 14 months, I love about Teac give me option to run 2 difference system, you can switch output between RCA or XLR. Last week I got the deal from Teac outlet for Teac CG-10M Master Clock Generator, the combo make big difference. 

Ayre QX-8 does both and is far better sound quality than others at this level!

server 100%. i recently got a taiko extreme and wrote specifically about this server vs. dac stuff in my thread on whatsbest. this is the thread itself: https://www.whatsbestforum.com/threads/living-at-the-extreme-i-bought-a-taiko-extreme-and-then-this-...

ive had a couple servers leading up to this and as a computer scientist/data scientist i was skeptical on any differences that would show up in 1's and 0's but the extreme, to my ears, is an even bigger upgrade than my amp. however, it's like an mbl101e extreme: it's great but hard to rec due to the sheer cost.

you're asking about different servers and streamers so maybe my experience with the extreme and rockna wavedream net and metrum ambre may offer some comparison points. i don't check agon forums often but i'm happy to answer questions. i don't get email notifications which is why i forget to hop by here. feel free to dm me too if that's easier