My Peavey Basic 112 has one input for an instrument and its fine except when I went shopping for a drum machine. Thats when I realized that another 1/4 jack would be helpful. The more expensive machines have a jack to plug the instrument into and an output to plug the machine into the amp. The sales man suggested a mixer (70 to 80 dollars ) but I was curious about anothr, less expensive method. Maybe a splitter or a two way.