It seems Clarion has a sealed board , but there are so many other
components that cant be sealed that long life is impossible, and
unrealistic.
Speakers are mechanical and deteriorate at a % per hr of use or
exposure . Ex. 20 yr old Ampeg 8 x 10" are 75 % less efficent
than new when compared to a new 2 x 10 for SPL at 1 watt @ 1 mete

Point is speakers lose Effenciency and Frequency response after
break in period . So you also have a replacment date with
speakers, They WEAR out as does anything else . Marine - C