I found this version on Youtube to give you a taste---although it's not Stirling's choice and I apologize. He wrote an incredible article none the less.
...(Blogged by Stirling Newberry)
George Crumb's "Black Angels" has proven to be one of the most durable works of the late 20th century, written for electric string quartet, it combines simple haunting sounds in places, with medievalisms and studied references. As the composer admitted later, the subject of the work is the Vietnam war. A recent recording by the Miro Quartet available on iTunes or through their website reaches into this work for the present. The work is in 3 movements, cast in 13 parts, some so short that they are gone almost as soon as they arrive, and none longer than 4 minutes, the entire work lasts only 20 minutes.