I always read that (solid state) amps and dacs dont colour the sound. I would like to see an article, where someone did a blind test to proof that.
It's more that the differences between their outputs, which is the only thing that could go into any sound signature, are close enough that differentiating between two amps or DAC's of comparable specs within design limits is going to be effectively impossible.
When the 'coloring' is below a certain level, it isn't going to be discernable.
It's not about an article that proves it. It's about a lack of (controlled) evidence to the contrary.
So far, not a single soul has come in this forum and demonstrated otherwise, despite a mountain of claims of how even the wives in the kitchen could hear the difference... Just don't ask them to do it when they can't peek.
Alpha waves or something.