All that said about the Yes albums, as great as they are, and every Yes fan should have these definitive versions, at the end of the day they're analog recordings from the 1970s, not exactly state of the art in transparency or realism. To a lesser extent this also applies to the Jennifer Warnes, Tracy Chapman and other albums common used for system testing. They were great for their time and still are good, but there are modern recordings that are even better especially for listening for midrange transparency and detail. That said, the Floyd Toole list of recordings is a good start, even if reference quality has moved forward since then.