I think it would be kind of cool to be able to set up some type of speaker item that could be wired to a device that works like the instruments. You would interact with it and choose your song just like you do with the instruments but the sound would be projected from all the speakers that you wired to the device. This would allow to play music not only in a larger area, but would allow you to do other things while it plays seeing as the music stops with instruments as soon as you switch items.
So, basically, we need to add Amplifiers in the game. OH MY GOSH YES. No Amp is complete without a pedal! Bahaha, this is awesome. +1 to you all. Great ideas!