Lifespan of amps and preamps?


Hello.  I have been listening to the same NAD 1240, Adcom GFA 535, and B&W dm 620s since I was 20 in 1990 (it was a big deal to buy all that as a 20 year old kid...).  Other than doing a thorough cleaning on the adcom a few years back when it stopped working, I have literally done nothing to these components. 

Are they totally dated, meaning past their intended lifespan from an internal component perspective?  I have to say it all still sounds really good to me.  But I never really listen to other systems.
Thank you for any input!
Scott.
cruxarche
It sounds to me as though you want a green light to spend money
again after your last investment 30 years back. 

If you follow these forums you must know you either care more about
money than SQ or you are just F-ing with us.

Fess up!!
Nice system and if you are happy then good on you. You also know that the equipment was cared for. If the capacitors are not swollen, or leaking you should be fine.

There is some good input concerning a good DAC and streaming. Consider looking in better source quality and music selection, first. Pardon, if I assumed you haven’t already as you didn’t mention your source material. Qobuz is a streaming service that provides a large selection of hi-rez music. A quality streamer such as a dedicated NUC computer running Roon (software musical interface) as it functions as a utility is economical, fairly east to set-up and works well IMO.  Happy listening.
Hi OP, 

I myself love vintage and old gear. I have a Scott 340b, laboriously restored last year. Good sound is good sound. I'd say if you are happy and want to keep your system, then do the necessary maintenance and enjoy your system. For another 20 years. 
I used to have a Nad amp bought before I was 20. It worked many years but finally gave up. I now use a Rega Brio and it sounds a bit better. I already had a dac but bought a Raspberry Pi as a streamer. It works great and is a cheap upgrade if you have a dac. You can also buy one with a dac like the Hifiberry. I would start with this before changing anything Else and also start saving for new amps since they may stop working.
Never change a running system... But if you want to get an upgrade, you can also have a deeper look on used (but not vintage) equipment. Many of the high end gems I got over the last years were used but in great shape. Never forget that also loudspeakers are ageing over the years. And that technology advances. I recently tested the new Monitor Audio Gold 200 and it outclassed my Infinity Kappa 7 II Series 2 in almost every way you can imagine despite of being significantly smaller: more resolution, more precision and very clear bass. So visit some dealers with a good portfolio and proper showrooms, discover the 2020 high end world and enjoy!!!

Greetz, Hans