Some components too old now?

@vinyloid,
Yes, I got the same take on those thread. So, maybe I'm wrong. The only way to tell is try and audition some more contemporary DAC's. Though I have to say DAC's from the 90's never contemplated the high resolution being offered today.
Re USB, a touchy subject...
For me, I loathe USB. Way too twitchy and dependent upon all the equipment around it. Just look at all the products offered to help clean up the USB signal.
I prefer optical. You just can't pinch it -(like Verizon did. It took 9 months for a tech to find the problem of my services dropping erratically).
Bob

I had my my Classe Audio preamp and amplifer since 1990 and only changed as I blew up the amplifier trying to adjust DC offset on amplifier.   My Magnalab tuner has been going on 30 years.    If you are happy with the sound no reason to change out.   I do agree that digital has come a long way particularly in handling jitter.   A reasonably priced DAC may be in order.   

If money is constrained I would highly recommend yo listen to Schiit.

That's the problem. The Schiit is plentiful. We need upgrades! :)

I have to applaud the music loving OP and a couple of other posters for getting a system you love and just...*loving it* for 20 & 30 years. It screams 'mentally stable'.
I know I'm not alone when I say there have been about a dozen amps in my life during that span. And PREAMPS. Christ, I can't even remember more than a handful of 'em.
Another option for the OP, if you love your stuff that much, perhaps you might think about 'modding' your pieces with some, if not all, of the caps replaced. Look at it like preventive maintenance, and it is. Old is magnificent, but caps do dry out.

So you can try out a Schiit Bitfrost MB directly from Schiit. If you don't hear a moving difference, bounce it back. They take returns.
And the mods, you can spend anywhere from a couple of hundred to a serious $600 or so. Depends on who, what, where.

I think where audio has improved the most since your last major gear purchases in two area's.

In both digital but really the most amazing growth is the outstanding sound you can get on a real budget and not an audiophile budget so to speak. Great sounding products for prices that have never offered this level of performance in the past.

I will hook you up - I just found these for you that will make a versatile, modern and seriously good system for money that just wasn't available in the past. 

Use your current amp and cd player as a transport.

$330 - Elac UniFi UB-5 Book Shelf Speakers
https://www.audiogon.com/listings/lis9ab5i-elac-uni-fi-ub5-bookshelf-speakers-black-finish-demo-moni...

$330 - Schiit Bifrost DAC D/A Converter; USB
https://www.audiogon.com/listings/lis9943i-schiit-bifrost-dac-d-a-converter-usb-15593-da-converters

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If you can afford a little more money this below will be entire system re-fit for dirt cheap with some reviews for you to read also. Insane level of performance for dollar spend that just should not be possible but is. 

$689 - Tower Speakers 
https://www.audiogon.com/listings/lis9ab62-elac-uni-fi-uf-5-floorstanding-full-range-speakers-black-...

https://www.cnet.com/reviews/elac-uni-fi-uf5-review/
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$799 - Stereo Amp, Preamp, DAC for CD and PC Audio 
https://www.audiogon.com/listings/lis9a1fg-peachtree-audio-nova-125-hybrid-integrated-amplifier-w-bu...

https://www.stereophile.com/content/peachtree-audio-nova125-integrated-amplifier-page-2

You don't need to research or look into anything else.

Use your CD player for a transport and your desk top PC for Tidal - Roon and have access to thousands of albums on your smartphone with a level of sound that your current system could not dream of for a sum of money that is very reasonable. 

Sure your system now is fine but this stuff will leverage the growth in performance for dollar spent better then maybe anything else you could find after months and months and research and I did it all for you in 5 minutes, 

Your welcome :)

 

Whilst I appreciate your advice @fsmithjack I personally far prefer going to my vinyl and CD shelves than turning on a computer or hard drive. Call me old fashioned. There’s something immensely pleasurable about simply handling those records and CDs that are associated with many personal memories. I could never get used to using a hard drive or streaming as it wouldn’t feel right. (I do listen to music on an iPhone when I travel on the train though!)
I’m also very comfortable with my other kit and those are the bits I have changed over the years. I think I’ve been through at least four turntables, three power amps and five pairs of speakers over the years - I only mentioned the old bits I hadn’t seen fit to change as I’ve been very happy with them.
I guess following all the advice, it’s the DAC that I’m now focusing on...