For artistic inspiration, I would highly recommend Kevin Drumm's
"Imperial Distortion" CD, which was composed using very simple filter/EQ
feedback loops. Raphael Toral's "Aeriola Frequency" and "Cyclorama Lift
3" CDs also use a "no input" technique of delays and equalizers, as do
all of Toshimaru Nakamura's famous "No Input Mixer" recordings (although
he uses a digital delay looper extensively to create rhythmic patterns).