How to perform the Software Update
To perform the update, extract the downloaded files to a USB stick (files available on NAD's Website), turn off the c390 off at the wall, insert the USB stick in the front of the unit. Then press and hold the standby button and flick the power back on. Keep holding the power button until the unit displays 'Updating'. Once the process is complete, the C 390 will put itself into Standby. The update has completed successfully!
How to perform the Room EQ
You will need an SPL meter and the USB stick with the setup files. Make sure that the 390 is on and the USB stick is in the front port. From the listening position, press and hold 'EQ' on the remote for 3 seconds. The amp will enter EQ setup mode and begin playing test files from the USB stick. The amplifier will play a 1kHz tone at reference, so it should read 80db on your SPL meter. Adjust your volume until it does. The C390 will then play a 240 hz tone, and you can use the up and down arrows on the remote to set the level until the meter again reads 80db. Repeat this process for 180hs, 120hz, 90hz, 60hz, and 40hz. During this time play, stop, pause, skip forward and skip back all function to navigate around to the different tones.
After this, there will be a long sweep and a short sweep tone. This tone should read about evenly on your SPL Meter. At this time, you can use the up and down arrows to adjust the 'Q', or the width of the EQ.
The Room EQ is now complete.