Why in some instances does changing streamers makes a bigger difference?

There like computers they have different engineers designing and differing levels of quality parts. The ess dac chip is advertised at around 200$ but some companies charge 109 pluss k for them. Then we could talk about wire and is there a difference in cables as I've seen some advertised > 70 k. Some like the all in one because they have a shorter distance between components.hope you have audio stores or audio clubs you can go listen to on different components. Enjoy the search.

I dont know much about streamers. Ive only had and still use Bluesound Node 2i using ethernet cable. I really like the app. Very consistant streaming, Qobuz. No issues after 4 years.

A noticeable improvement occured after moding the sps to a board that lets me use an external lps, Keces in my case. Also, bypassed the Nodes dac and running it through, first, a Geshelli J2 now a MDHT Orchid with upgrade tubes. 

Im happy with the sound even though vinyl is the better part of my system. Like vinyl there are very good, good and bad digital recordings.

 I would probably have to make a huge upgrade in a streamer to notice a significant improvement.

It depends on how the streamer and the DAC are connected.  In the stuff below the capitalized DAC refers to the whole component and dac revers to the innermost guts - the chip that turns the digital data into an analog voltage/current.

Critical to sound quality are the accuracy of the digital to analog conversion, the filtering of that process (which initially yields a "staircase" waveform) to create a smother analog signal.  These are not affected by the streamer - assuming it sends the correct data to the DAC.

And then there is the timing of the digital to analog conversion steps, when digital data is strobed into the dac chips by a clock signal. If that strobing is not done at precise intervals - phase noise or jitter - the waveform is distorted, so a key contributor to SQ is the accuracy of the clock, not just its frequency but how precisely regular it is.  This is why DAC designers (and Streamer designers) go to great lengths to ensure accurate and stable clocks.

If the connection is IIS (I2S) then that clock is transmitted from the streamer to the DAC in the cable.   If your streamer's clock is better than the DAC's, and you have a first class cable, your SQ will improve. Similarly with Coax and Toslink the clocking is to some extent dependent on the streamer, hence SQ will depend to a greater or lesser extent on the streamer in addition to the DAC.

If you use Asynchronous USB the SQ is probably unaffected by the streamer as the data is read by the DAC, on request, into a first-in-first-out buffer (a chunk of RAM) and is strobed into the actual dac chips by the DAC's clock.  So the analog output is isolated from timing errors (jitter) from the digital source.

The author of the YouTube makes this point at about 7:45.

I have done an experiment on my DAC, using USB, if I "pull the plug" on the USB cable there is a small but just there delay before the sound stops as the data has been transferred into the DAC's buffer.

There is also the issue of (loosely speaking) electrical noise, but the same argument applies - the DAC should be implemented to isolate its analog output from glitches on the digital cable, power cable and ground. If changing your streamer affects the sound IT IS YOUR DAC THAT IS DEFICIENT.

I am probably going to get yelled at for writing this but IMHO put your $$$ in the DAC.  Make sure it supports USB. If that component was truly well designed, engineered and implemented, and you are using an OK USB cable putting $$$ into the digital componentry and wiring before that is probably not going to change your listening experience - assuming an OK streamer and OK network.

My implementation is somewhat extreme, the DAC is the Esoteric K-01XDSE, with a Stanford Research FS 725 Rubidium clock - accounting for 90%+ of the cost of the digital equipment, and the sound is superb, the Esoteric engineers have gone to extremes to create this isolation, perhaps others have not.

I have tried changing USB cables (Cardas vs a cable than came with a printer), Streamers (Aurender vs Eversolo T8), Internet connections (wired vs WiFi) - no difference.  Using the DAC's internal clock vs. the External clock - noticeable soundstage differences even though the DAC's clock is excellent. Using Coax or Toslink instead of USB - a definite drop off.

Once the signal is in the analog domain it is a different story, everything on or near the signal path matters.

I rewatched the video more carefully (initially I'd just watched bits and then fast forwarded.)  I think it is a first class piece.

I have said in other threads that the engineering of the DAC is critical for consistency.  Esoteric is, first and foremost an engineering company and achieves that isolation of output from input glitches - and then gets great SQ.  That said, it is altogether possible that there are DACs that make beautiful music only when fed with clean input.  If such a DAC meets your SQ needs then your streamer may well be important - the DAC designer put their efforts into the sound, perhaps to meet a price point.

I think the main point is that connected equipment interacts electrically and that these interactions cause DAC clock timing perturbation, causes faults in the D/A conversion accuracy. This makes sense to me... we can send data across the planet unchanged but when we try to convert it to analog it becomes vulnerable to corruption.