I chose to add a volume slider to the object as I felt it needed something to convey that it is a musical device. I really like the volume sliders found on the Phillips 22GF Portable Record Player pictured below.
I wanted to replicate something similar to this on the object. I crafted my own buy splitting a 3.5mm audio cable and attaching two logarithmic potentiometer sliders to the left and right wires. Fixing the two potentiometers together and locking their sliders meant I could control the volume and maintain a stereo output.