Read the reviews of the posh DACs. All of the review set-ups include data stream cleansers. The reason is that they matter.
What I see when I read them are typically ZERO controls, lots of convoluted half science/half WTF, combined with other products that they are promoting that also generally don't matter.
They will then often start writing prose that, with a few changed words, could easily be considered pornographic. Usually they give away their own ignorance early and often (cough cough Darko cough cough), but other times they aren't as eye rollingly ridiculous, and can be very convincing.
They are salesmen. Money is at stake, they are able to be very convincing.
Controlled tests bridge that gap. Education does too.
I have never noticed a difference in sound quality between streaming via network, wifi/optical, coax, USB stick, AES, airplay, or anything else I've connected with.
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If you have any actual data, studies, or science that backs up what you are saying, please share it. Uncontrolled anecdotal subjective experience sharing isn't going to get very far.
Oh, I'm incorrect. They certainly do matter to their profit margins, because bullshit products are very often shockingly cheap to make (look at the cable world... Unbelievable it isn't illegal). I don't believe in Woo. People that try to sell me stuff that requires belief in unknown physics, I'm not interested in.