usually KRELL / LEVINSON would last a lifetime, I have my KRELL DAC still alive after all these years since 1992 when I was in College. There was a period of time I never unplugged it so basically it was Power-On all the time coz it didnt have a Power Switch, not to mention being hit by Brown-Outs, Sudden Low Voltage drops, A 10second power outage w/c brings the current roaring back to life to more than 260v. with all of these then w/out the use of AVRs or Line Conditioner & its still alive & well up to now.
But I had friends who had those KSA models that really died down too, the KRCs, FPBs, KPS models I think were much the durable ones. I have a KAV-250cd still on my shelf as a back up player for my older player but this was not tough enough to the test of time (not more than 2yrs) as gradually it started not to read CDs properly until it could not read anything anymore
, The older player is still in tip tough shape for more than 23yrs.