Class A amplifiers

Class A amps run hot! And it does lower there life expectancy. With that said if you dont mind the heat it gives off (like some of us that live in Texas do) and you dont mind sending it in after a period of years (it will be needed) then go for it! :-)

P.S. I have a old ADCOM GFA 555 that is class AB and it still sounds awesome today after 30 years because it runs cool to warm never hot like fry an egg hot that class A amps get. Im not comparing the sound, of course the Krell or Mark Levinson amps do sound better but at a much higher cost. If I were the OP I would ditch the idea for a highly investigated and informed used McIntosh amp and be done with all this "amp runs Hot, Class A, send in for service" talk. Find a special amp that MAC makes, do some research, they do make some great amplifiers (its what they do best)

Matt M

totally BS the design engineering and parts quality are the most important in their longevity.
I had a pass labs for over 15 years from the late the 90s class A amps  without any issues.

Like most blanket statements, its no true but has some kernel of truth.  Class-A amps typically run hot because they dissipate 100% (actually in most cases, 200%) of their rated power all the time. But that is a design condition and ought to be accounted for so that it is irrelevant.
Depending on how they are designed, cooled and parts chosen, class-A operation, and its attendant heat generation, can have very little effect  - or can be a long term issue.  I have hundreds of units that I designed in the field, many approaching 30 or over 30 years old with essentially no failures due to accumulated heat. While these are not pure class-A, they are very high bias amplifiers that dissipate a LOT of power; but they are designed for it.
The primary components harmed by heat are electrolytic capacitors.  transistors can run very hot with no ill effect, and most resistors can too unless the are directly over-powered (e.g. run at or near their rating or 1/4w, 1/2w or whatever).  Film caps too typically are immune unless its so hot they melt -- and that's HOT.
I'm sure there are some poorly designed amps out there. Avoid them :-)

Add my name to the Nelson Pass Fan Club.
His amplifiers have a reputation for being highly dependable.
I have (and Love) a First Watt Sit-3; It does not generate much heat at all and I expect many years of trouble-free service from it, as that would be consistent with his company's offerings and his design philosophy. Pure, simple and with few 'moving parts'!
Happy Trails to you, Bear.............

Boulder 2060.
Still reliable.