It's useful at this point to explain the innovation which Riley brought to the table when In C was first released. 53 phrases of various lengths are looped, by instruments of the players' choosing, at times of their choosing, with a few rough guidelines; all the while a piano heartbeat plays the note C in quavers. This means that the finished article is owned as much, compositionally, by the musicians who play the piece as by Riley himself. It also means that the 20 or so recordings (and many more performances) of the piece are all individual, to a greater or lesser extent. This was a significant diversion from the well-established norm (which is still most familiar), where the notes are strictly defined and there is comparatively little freedom for the conductor and instrumentalists to paraphrase the composer through variations in tempo or dynamics.
Of the several interpretations that this writer has heard, this is the one which stands out the most, both in terms of originality and conceptual depth. This is In C as would be performed by Godspeed You Black Emperor!: In the opening minutes, harmonic feedback and clarinet yelps laid over a bedrock of drone and crashing cymbals give way to the piano, and then violin-bowed guitars build to a grandiose dischord, a feature which re-emerges several times over the course of the hour. The thing which really sets this version apart, though, is its immediacy: Whereas the 1968 original is a more or less homogeneous suspension of rhythmic subtlety and, to a lesser extent, harmonic exploration, this recording amplifies the contrasts, building slowly and dying suddenly. (It's probably pushing the envelope further than originally intended, but one suspects that Riley would approve.)
Dennis De Santis (who some may know from his arrangements of Autechre for chamber orchestra) contributes granular delay and reverb processing which becomes more prominent during the piece's latter stages, taking the material from early on and tweaking it into a cavernous, tectonic beast which twists and bounces. It'll more than satisfy the highbrow technologists, but this is only the most obvious piece of evidence presented in an essay which blends a wide range of musical idioms to make its point. At 34 minutes, for example, gypsy flavoured accordions give way to a spasmodic carnival of claps and clippity clops that typifies Godspeed's more joyous moments, before settling back into quiet, dizzy oscillations.
You can analyse the rhythms, harmonies and ideas presented, or you can just let them carry you. Perhaps the most significant difference between classical music and popular is its greater capacity to offer pleasure on an academic and emotional level at once. Ghostly's edition of In C brings out both of these aspects in a recording which promises to continue to reveal its details, and educate accordingly.