This is a tough question. Solid state gear is quite reliable and rarely have problems, but, when some transistors go, they cannot be replaced and the amp is toast. Tube gear is more prone to failure, but older classic tube gear can be repaired and returned to service for a very long time. Some ultra high quality tube gear can operate without any repairs or parts replacement for many decades. A friend has a Western Electric 124 amp that sounds great that has all original parts that is probably 70 years old. My amp is a Western Electric 133 re-build with almost all of the parts being vintage (all except the power transformer and choke, input jacks and binding posts), and it has operated with no issues for about 12 years (no tube changes, and the tubes were old when I got the amp).
Amplifier Longevity Question
When I got started with quality two-channel equipment, after my first pair of decent speakers (B&W CDM-7NTs), I bought a Magnum Dynalab MD208 receiver. This was in approx. 2001; a leap of faith, based mostly on a Stereophile review. About a year later, after upgrading speakers, I bought a McIntosh MC402 power amp, and used the Magnum Dynalab only as a preamp and tuner.
Although I've since changed sources, speakers, and cabling, the MD208 and MC402 are still in use today. (For about 7 years, they weren't used much; before and since they've been played daily, or close to daily.) I have no complaints about sound quality. I have noticed zero SQ degradation, despite two household moves, and placement in living rooms for the entire period. My system (with Sonus Faber speakers) sounds good to me, and to my wife, a retired classical musician. I wish the MC402 didn't weigh about 115 lbs, and would rather that our last movers hadn't lost the MD208's remote, and somehow caused the volume knob to decrease its immediate responsiveness (a very minor issue), but otherwise, I have nothing to complain about.
But nothing last forever. And at this point, a decent audiophile system is important to us. I'm not itching to make a change, but I am curious to get some sense from my fellow A'goners about the remaining useful life of these two components, which have served me well. What should I reasonably expect?
Thanks in advance for your thoughts.