If you want to hear something amazing, find a copy of Live from New York City, 1967. I'd heard plenty of Simon & Garfunkel before that, including many of their studio albums and some later live recordings; I enjoyed them but they didn't stand out to me. This album was eye-opening; it wasn't the songs (a bit over-earnest IMHO) nor somehow virtuoso individual performance, but the craftsmanship of their duet is beyond what I imagined for the genre, beyond anything I've heard from them or other singers. Perhaps their attention to their craft wasn't so obsessive later in their careers (I don't know), but you won't think of them or duets the same way again.