What's truly sad is that we missed a quarter century during which Susan Boyle could have been singing to us. Just listen to her early version of "Cry Me a River".
Heck, Mozart woulda loved this. I reckon the dissenters don't care for the Kronos Quartet's version of Purple Rain, either. Or the cowbells in Mahler, or the wind machine Strauss's Alpine Symphony, or....
Everyone responding to this should go to Amazon, or another source, and for a buck download the 6:45 version of Chuncho...from Sumac's live performance on the o.p. RECITAL CD. If anything, it's even more astonishing.
There is an excellent book on Ms. Sumac that clarifies a great deal about her, debunks tall tales, and goes into tremendous detail on her life and talent. Available from Amazon, among other places.
This may not be her most famous number, but I think it's the most purely beautiful.