It depends on time and temperature. If they are at low ambient temp. then most likely they will last for 50 years. If playback increases temperature they will dry out sooner, but 8 hours a week is like no use at all. I would not worry. Will you last 50 years? :)
When capacitors dry out ESR increases usually reducing bass control (wooly bass) and/or increasing audible 100/120Hz ripple. Capacitor might also get hotter because of high RMS value of charging current and increased ESR.
When capacitors dry out ESR increases usually reducing bass control (wooly bass) and/or increasing audible 100/120Hz ripple. Capacitor might also get hotter because of high RMS value of charging current and increased ESR.