Hi can anyone tell you how to 'factory reset' a Yamaha DSP-A1 AV amplifier?

To factory reset a Yamaha DSP-A1 AV amplifier, you typically need to locate the reset button on the unit. This button is often found on the back panel of the amplifier. Press and hold the reset button for a few seconds until the unit resets to its factory settings. Keep in mind that this process may vary slightly depending on the specific model of the amplifier, so it's always a good idea to consult the user manual for detailed instructions.