Streamer with built in DAC...is there much difference between brands?

Understood on the rest of the system but is something like a WiiM Ultra with a $500ish new/used external DAC (Topping D90?) going to be a better option than an $800ish Eversolo DMP-A6 Gen 2 using the built-in DAC?

@asahitoro  A big benefit of separates is you can sell/upgrade each unit individually, and it just offers more flexibility of choices in general. 

The big advantage of an all in one is direct wire of internals short signal path. I have eversolo 8 and 10 and like it.my aurender just went out of business,poop!  I do have separates. Denafrips terminator 15, and others. Just bought the new tube dac from apos and need to try it. Asr does alot of reviews on these less expensive units. As for the others read the reviews i think it was the new 1k  reviewed as well as > 10k.enjoy the homework.

@mark200mph nice.  I heard both Eversolos recently.  The 10 in particular really impressed me.  Quite the looker and top notch sound to boot using the TOTL Ess Sabre DAC.  

I had a Node 2i feeding a digital signal into my moded PS Audio Directstream DAC Mk1 over a coax connection. When I moded the 2i with a Teddy Pardo LPS there was a huge upgrade to the SQ. Two months ago I purchased the new Eversolo T8 streaming transport. Again, there was an improvement to the SQ, but not as large as the improvement when I switched the 2i to the LPS. I'm using the I2s connection from the T8 to the dac. One of the most important considerations in a streamer is the OS; is it intuitive and user friendly, and does it support the streaming services that you use? I have wanted to upgrade the streamer for some time, but until now was unable to find one that supported the two streaming services that I use most, Amazon HD and Idagio. The T8 supports both of these, plus many more. And the OS is very good.

The simple answer is NO, if you are shopping at the same price point but YES if you are moving up the price ladder.  But the orders of magnitude of improvement don't correlate...spending twice as much won't give you double the improvement except possibly the low end where the dac upgrade can be a big factor.  The incremental improvements become less as the prices go up.  I agree with @ghdprentice system cost breakdown.  I think it is a good target to shoot for as one upgrades their rig.