Some albums just have the perfect name, and Amon Duul's debut nails that to a T. Obscure upon release and obscure even now, for all the cult appeal, Underground is music at its most experimental and relentlessly uncommercial, using late-'60s inspirations as a launching ground for what came to be described as Krautrock. Psych-folk was another common term, one which applies just fine to much of the music here, feeling like an enthusiastic medieval festival gone just out of control enough, and with electricity to boot. Taken from a jam session from the previous year, but treated with many studio effects that enhance the strangeness of the collection, Underground rocks to its own weird beat.