We actually did something more along the lines of your first suggestion - we were asking for difference not specifically “which is better” because actually “bet

We actually did something more along the lines of your first suggestion - we were asking for difference not specifically “which is better” because actually “better” is entirely contextual (and actually this was part of the point - that some people actually prefer lower quality audio because it’s what they are used to). I think (it’s a long time ago now) that we played each set which was two or three samples twice and rather than asking which was “original” I think we asked them to score for clarity, richness and which they preferred - and then to make a guess about which was a higher/lower quality source file. Like I say, it wasn’t a rigorously scientific experiment but it was in the context of a conference about evolution of audio standards and what that meant for audio delivery from labels/distributors to DSPs.