Speaking of transparency.....it was when I read Harry Pearson say in a review of a loudspeaker that it was "transparent in the same way the original is" that I realized he didn’t actually understand what the term transparent means. If the original were "transparent", you wouldn’t hear it! That's like saying a photo copy is as transparent as the original. If the original were transparent, there would be nothing to see or copy!
Transparent means what J. Gordon Holt said it did: the ability of a component to be invisible, like an open window. Lack of transparency (JGH sometimes likened that to a layer of what he called "scrim" placed between source and listener) is any veiling, adding of texture, change in vocal and/or instrumental timbre and color, reducing of dynamic contrasts, hardening, or any other artifact added to the original; Doug Sax performed bypass tests to evaluate the transparency of any piece of gear he was considering for use in his studio. If the insertion of the component was absolutely undetectable, it was perfectly transparent. If it added any of the above, it wasn’t. Interestingly, in spite of their unequalled transparency, Sax didn’t choose ESL loudspeakers for monitoring his recording and mastering work.