@ ahidler: my 1978 Son of Ampzilla has been in daily use (always on - never off) for the past 2+ years! Still sounds excellent! So your vintage NAD 3020 and 3240 are probably ok too! It's anybody's guess how long caps operated within their voltage and temperature rating will last! BTW, I used to own two 3020's long ago - great sounding integrated amps!
