You say, "If the Ethernet cable is altering the output of the DAC then it should be captured in the tracks I provided." Perhaps. That will happen if the system is good enough. If it's poor then likely the difference will not be noticeable. Seriously, a couple hundred dollar system is what you are putting up for evidence? How about you get some serious gear and do the test? Audiophilia is not the reduction of quality to the lowest common denominator. You WILL get mediocre sound that way.
I want to point out the gross error in 'logic' that is made by someone that has no idea what they are talking about.
If I capture a track into my ADC and then I overlay it back over the original PCM from the 24/192 download that I recorded from and FFT shows less than a .1 dB variation in Amplitude response (or any other FFT analysis shows virtually null) then I have one simple question:
How is a $250 system able to produce such accuracy if it's not 'some serious gear'?
How about this. We setup your DAC and Streamer into an ADC and we setup my $250 computer into your DAC and into an ADC. Capture 9 tracks with one system. 1 track with the other. You can then analyze however you would like for as long as you like (you won't know which is which) and let us know which track is different from the other 9 and if it's the track from the $250 system or your streamer.
This should be a no problem for someone with such a highly resolving system.