Lifespan of amps and preamps?

Well, these components have provided joy for 30 years. That's spanning the gulf war, the dotcom bust, the great recession to the current global pandemic. That's impressive. If you updated all of these components now, that should get you to age 80. Then, time to update again......

@cruxarche,   Kudos to you for acquiring a system like that at such a young age.  Until recently, I was using a Sony AV receiver, Jensen speakers and a Pioneer CD changer, all 25-30+ years old.  They still sounded pretty good to me, but at this advanced age (65) I decided to treat myself to entry level audiophile equipment.  My nephew now uses my old system and is happy with it.

Along with the advantages noted of newer equipment, I have seen people on this forum and elsewhere state that the quality of equipment has declined the past 20 years.  Unless you are paying big bucks, corners are cut to reach a price point.  For that reason, some people seek out vintage equipment and then have it checked by a qualified technician for recapping or what replacement is deemed necessary.  If, as you say, funds are limited, you might need to be frugal in trying to upgrade your sound (I have no idea what restoration of vintage equipment costs, but people do it.  I recommend videos by a guy on YouTube that does excellent work — xraytonyb.  Check it out).

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.