@soix don't shoot the messenger. I'm merely asking a technical "why?". I also believe the old axiom that a fool and his money are soon parted if they aren't at least a bit skeptical. I'm not arguing with you or anyone else on DACs. They obviously have sonic characteristics because at the end of the chain, they are analog devices, with design choices made to give the best sound at any price point.
But I'm simply not sold on "mere" transports being all that different. Either they should be passing the correct data stream or they aren't. There's no middle ground when it comes to digital - or at least there shouldn't be.
So, if there is, (and many on here say there is) there inherently should be some way of measuring that and seeing why. That's all I'm asking for. A valid engineering answer to the "why?"
And just as important for manufacturers would be understanding that "why" and applying it to their own products. A black box is a black box. Applying a time domain transfer function to one box should be able to make it sound very nearly identical to the other one and do so for perhaps less money.
Bob Carver did this decades ago with some of his amplifiers and all the audiophiles agreed, his amp sounded exactly the same as the one he was modeling.
At the end of the day, I'm just looking for "why?" This isn't magical fairy dust. It all is based on knowledge of electrical engineering, the technology available (when the bean counters allow it), design philosophy, and psychoacoustics.
Happy listening!