There's an article in the recent edition of Copper Magazine that talks about Owsley Stanley and The Greatful Dead's sound system known as the wall of sound.
"The stage system stood forty feet high and seventy feet wide and sported 88 15 inch JBL speakers, 174 12-inch JBL speakers, 288 5-inch JBL speakers, (dude, remember how popular JBLs were?) and 54 Electro-Voice tweeters. The sound was powered by 26,000 watts generated by 55 McIntosh MC2300 amps. Giddyup."