From the manual:
NAC S1 and NAP S1 illumination has normal and vivid operational modes and can also be adjusted for brightness. Illumination control covers button illumination, volume control illumination, input display illumination and logo illumination.
NOTE . If your preamplifier and power amplifiers are connected using CAN bus, illumination adjustments will automatically apply to all.
Illumination modes can be alternately selected by pressing the top panel disp button or the handset disp key.
In vivid mode, all illumination will remain permanently lit while the units are operational. Vivid mode illumination brightness can be adjusted using the handset disp- and disp+ keys.
In normal illumination mode only logo illumination remains lit permanently. Button illumination, volume control illumination and input display illumination will fade up on control operations and
fade out again three seconds following control operations. Normal mode illumination brightness can be adjusted using the handset disp- and disp+ keys.
NOTE . Normal illumination mode fade-out following switch-on is ten seconds
