Old SS amps

@OP As Hk_fan says above, it is brand and maybe even model dependent. If you are looking at twenty years plus, especially if it's a high powered amp, you can expect to be looking at a PSU reservoir caps replacement - though not necessarily immediately. A visual inspection will show if there are major dangers. However, caps are not the only failure point in an amplifier - e.g. rectifiers and output devices are also prone to failure. And replacement components are not necessarily available. So it's basically a crapshoot. Gear can on on for ages or it can fail. I've seen old Quad 405s get beaten to death in studios and go on almost indefinitely. You pays your money and takes your chances.

I am currently using a pair of McIntosh MC501s that I bought used 20 years ago.  The drive 3.6 Maggies beautifully and have been rock solid all this time.  I believe I could sell them for what I paid, although I have no reason to do that.  Build quality is a real thing over time.

@bdp24 that old BEL amplifier is an excellent amp.  It produces a slightly warm overall musical sound with pretty good details, high and low end extension.  We compared it to a few modern day amps and it was the winner for producing overall musical pleasure.  I think it has 2 or 4 larger PS capacitors.  It was a very simple design that worked so well.

For those of you who say run away, you need to rethink this.  PS capacitors like Nichicon SuperThrou's probably run around $50 each so replacing four of them is not expensive.  We have a bunch of different 15-20 year old amps in for repair now.  Most have simple issues and customers just want to upgrade the caps, etc.  Once upgraded, current models you may be familiar with usually cannot compete.

My old Lafayette KT-550 tube amp in stock form still kicks the crap out of many current models and sometimes pretty significantly!
Upgraded older Counterpoint amplifiers also kick butt once upgraded (full/complete upgrade/modifications almost complete rebuilds with point to pint wiring ($2k-$3K).

You won't find many if at all new amplifiers with point-to-point wiring!

So for a $3K investment you get a fantastic upgraded product that kicks butt!  Great parts, great sound.

Happy Listening.

My Classe Model Fifteen amp is over 30 years old and performs perfectly. Never had any problems. It shares duty with my Cary Audio Six Pac mono blocks which have also been maintenance free other than tube replacements. 

J.Chip

I’ve got a Sim W-5 was told not to turn it off with risk of voiding a 10 year warranty. Fired it up the other day, plays and images like a champ. Great with tuff to drive loads as it almost will play into a dead short.