On record at least, Coro is one of Berio's least penetrable large-scale works. Physical space, the movement of sound on the stage that is so integral to the work, only vaguely registers here, and layers that need to be separated instead congeal into thick slabs of sounds. Given the density of the score, its sheer duration (57 minutes of continuous music) and its sombre character—what Berio describes as a ''single mood of dark suspension''—the piece is a challenge to sustained concentration, let alone to comprehension. But it is worth the effort. Reviewing the release of the work on LP in 1980, AW wrote of Coro as ''a highly personal, yet urgently communicative statement, persuasively performed'', all of which is manifestly true. Whether or not it is also ''well recorded'' is a different matter. As in the cases of other massive works of Coro's generation (Stockhausen's Gruppen and Carre are examples), it's hard to imagine how any recording can possibly transcend the condition of being helpful for reference and instead truly capture the experience of the live performance. Put another way, if this strange work does not entirely convince even on CD, then that is not necessarily any fault of the music itself.'