Amplifier Longevity Question

+1 @erik_squires

And I would say not just output transistors but any transistors. If an amp drifts out of spec, or if it is a Class A or AB amp and that constantly generates a lot of heat, the transistors can get exhausted and not perform their switching duties, fail and cause leakages or shortages that can send the amp to protection more or fry them.

Tantalum capacitors almost easily fail and can melt or bubble up with too much heat over time. Electrolytic capacitors typically don’t leak, but they just don’t store and deliver to their spec as they dry up, which starts to introduce distortion and/or thinness to the sound.

Transformers are generally incredibly durable and very difficult to ruin unless too much excess current fries a fuse that is built into it. And circuit boards are generally fine unless something causes a short to fry it, typically from one of the electrical components as described above. 

@blisshifi

You aren’t wrong, it has just been my experience that the output transistors are the one’s that are most likely to go out of fashion and impossible to find replacements for.

The small power transistors tend to be interchangeable or remain in production forever.

To answer the OP's question I was answering the question of"when will my gear die and not be fixable?" vs. how often will it need to be serviced.

@erik_squires Absolutely agree that the output transistors are typically the first to go of any transistors in the unit.

@gg107  Why not send in your MD to Canada (or maybe Buffalo, NY) and have them give it a tune up. I made the mistake of sending my MD102 to fix the reception drift and got back a MD108T. The MD108T is  great.

Very amusing, @yyzsantabarbara!  My dealings with MD have not been entirely satisfactory. I called them to see about getting a replacement remote; the person I spoke to said he would get back to me in a day or two.  I did not hear from MD; after about a week, I called and emailed them on the same issue.  They did not get back to me.  About a month later I called again.  No, they didn't have a replacement remote, and couldn't help me.  Great product, but unimpressive customer service.  

As for sending it in for a tune-up, I don't want to be without music for however long it would take (and I suspect MD would not be swift).  But, @yyzsantabarbara, were they timely with you?