It could be there? How would I test for noise?
Subjectively: ABX test between Computer->DAC and Computer->Network->Bridge->DAC.
Objectively: Plug Computer->DAC and Computer->Network->Bridge->DAC into a scope with plenty of dynamic range, play the usual test signals, and analyze/understand the differences.
The first one tells you if the difference matters to you personally. If you iterate the test over a population, you can determine whether it makes a difference to anyone.
The second one tells you what the differences are, and the nature/degree of differences present. There will always be some if you zoom in far enough. That’s just the nature of analyzing analog systems.
These are not easy/cheap tests to run, so in the real world, audiophiles don’t bother. Responsible HiFi manufacturers routinely do both during product development.
When we first brought our PC-in-a-box Sooloos products to Meridian in 2008, one of the first things they did was to put each product inside a metal room, measure what kind of EM/RF interference it was emitting, and measure how it impacted performance measured in the analog domain–and they found the results pretty amusingly bad compared to their usual standards.
I’m not an EE, but I know when to respect another engineer’s measurements and do my part fixing the problem. The end of that road was marked by the release of lightweight networked endpoints that fully met Meridian’s performance standards.