Sonics of Streaming

Reviewers, both here and in the audio press, speak of vast sonic differences among the many DAC-less streamers/network players on the market. Leaving aside features such as ease of use, variety of outputs etc., what internal design elements dictate inferiority/superiority in fidelity and the enormous range in pricing? My ancient analog brain can't grasp how Model X on a given ethernet cable can render streaming audio so differently from Model A+ on the same cable when both use the very same cables, DAC, amplification chain, and loudspeakers.

Advance thanks for a brief tutorial to guide my planned "upgrade." 
4 of my 5 do NOT exhibit the differences you allude to. Maybe try a different DAC. Or use a different cable.  
The only laggard is the first, a BluSound.
Streamers don’t all sound the same for the same reason that all DACs don’t sound the same. They’re still processing the digital signal, and slight differences in circuitry and components lead to slight differences in sound. 
Tried streaming at my cousins house with my music.
  Many songs Sounded flat to me.

   LP & CD, is the way to go.
it just sounds way better, bass tighter, guitar is much more realistic sounding, highs are not so subdued. 
 My main speakers are Energy RC-70s’, with the 600 MHz or hz roll off of the tweeter, a nice warm speaker, 
the tritons have a nice tweeter' much more powerful than my rc-70s’,
yet, the treble sounded even more subdued on much of the high treble music I listen to.


humble pie
thin lizzy 
john denver

much more, tried all types of music.

 Your ears may be different than mine, just not for me.

 Happy listening. 
 Enjoy the hunt, that’s the fun part.

I meant streamer/transports -- digital-out processors with no integrated DAC. For example, the Aurender N10 versus the N100H. 
I can speculate on why there are differences but this won’t be helpful to you because it will remain my speculation. Of course, this very question has been addressed in many related threads so you might find value in reading through them.  While YMMV, in my own experience, I found greater differences in moving upstream from a Bluesound node 2 (going into my outboard DAC) than I did in moving into a much nicer DAC. 

There are many on here who consistently claim there can be no difference or that they haven’t heard differences.  Fair enough.  They’re are a number of us here who do. Perhaps it’s placebo. Perhaps not.  

There’s really only one way for you to know.  If you already have a decently resolving system - audition a couple in home.  I would suggest you listen for spatial information (openness in soundstage width and depth) as opposed to tonal differences.  Lower quality units sound “flat” to me relative to nicer units. 

Hickamore - I too am mystified by this. Reading around, you can find that some $1000+ streamers use a Raspberry Pi to do the actual processing. A R-Pi is about $30. So what seems to matter is the first stage of output. The R-Pi 4 has fixed a problem earlier models had with the quality of the USB-out. I like coax out so I got a good quality HAT to sit on top of my R-Pi. This measures spectacularly well yet was not more than about $100. I’ve done blind listening tests comparing this R-Pi plus Allo $150 setup with my Node 2i running digital coax out, both with the same Ethernet in, both out to the same DAC. There was no difference at all to my ears. Or to my son’s younger and better qualified (and very fussy) ears.
Very interesting, thanks. I will also look up other threads possibly addressing the same question.