I have a Pioneer SX-300T and I can't understand how the combined volume/balance knob works. The knob has two rotating rings/switches, the outer for overall volume and the inner for what appears to be balance. That innermost knob is marked "Front LT" and "Rear RT". I don't know what that means! The main thing that doesn't make sense is that the rings turn with one another, unless I hold one while I turn the other. But I don't want to be holding the balance knob while I turn the volume up and down. Does anyone have any insight about this, perhaps from later Pioneer models? It's a handsome little unit that puts out better than rated power and good sound quality. Thank you!