There is a jumper in the 828 MK1 that allows you disconnect the main volume knob on the front panel from the 828 main outs. The 828 defaults where the volume knob controls both the headphone outputs and main outputs. There are instructions printed on the circuit board inside the 828, near the headphone output, which explain how to change the default. Simply power down the unit, unplug it (to avoid shock - very important), removing the cover, and move the plastic jumper labeled "Main Outs" from one set of pins to another as indicated on the circuit board. The "Fixed" position means no volume control. The "Variable" position means you get volume control with the front panel knob.