Okay, I know that a computer program is not technically an instrument, but it is as important as any of the instruments I use. This program literally turns your computer into a recording studio. With nothing more than a microphone, headphones, and of course all of the other musical instruments, I am able to single-handedly record multiple tracks, edit the tracks, and mix the tracks. And the best part, it is absolutely free! Audacity is an open source program, and I cannot adequately express my appreciation for the work put into this project.
Click Here to download Audacity