"Vintage" high end gear vs new and upgrade path?

Go all the way with the rega: motor, tone arm wire, sapphire sub platter, weight at end of tone arm, new platter in exchange for glass platter, and wind up with the sound of a Sota Sapphire.

I hate to mention it because there are few of them out there and I want them all, but the pairing of my vintage SA9800 and my KEF LS50s is nothing short of magical.  I have had several fellow audiophiles visit to listen and honestly it ruins them.  The combination of the rarely since achieved stats of the SA9800, careful setup and room placement and the clarity of the LS50s is spectacular.

As someone who can't hear any difference in audio equipment or paraphernalia, except in speakers and phono cartridges - including in blind tests - and since I gave up vinyl over 25 years ago, my focus is always on speaker upgrade and room treatment.

For 2-channel I use all vintage (Pioneer SA-8800, C-72/M-72, Kenwood 7030) - because I like the looks - with a Schiit Modi DAC (given my programming background and understanding of how they work, I doubt if I could tell one DAC from another, but this is one piece of equipment I haven't tested blind). Vintage doesn't sound any different to me. My second most important piece of equipment is a laptop with REW and UMIK-1.

If you like Magnepan it seems that's your first obvious upgrade path. I will be using Maggies (MG-10QR/CC3/MC1 tri-center) in the HT of my new house (unusual, I know, but I'm not a "dynamics" or SPL guy for TV or movies), but for most of the rock music I listen to I prefer speakers with flat FR on/off-axis (Revel, PSB, Paradigm Sigs, KEF Reference, Technics, etc. ... I own the Sigs and Technics, and would love to find a pair of KEF 201/2). I think Maggies are fine for classical and jazz. I think what everyone prefers in speakers is too variable for recommendations, but Toole has proven that most people prefer flatter FR in a blind setting.

My feeling is, if you can't hear it blind, it doesn't exist. I understand with the lack of brick-and-mortar it's getting harder to do, but if possible test blind on everything else before you buy. If you can hear a difference blind, fine. If not, it saves you a lot of money if your ears say "watts-is-watts and wire-is-wire". Unlike some of the hard-core "scientists", I think single-blind is close enough if you have the right person doing it.

And as a musician myself, forget trying to recreate the live experience. It's a Don Quixote-esque quest.

My opinions on vintage vs modern circuit design;

Vintage equipment is most likely using discrete class A circuit designs which IMHO are better sounding than anything modern built with op-amps. A good example is my Spectral DMC 10 phono stage. All discrete transistors and sounds wonderful. Since many discrete transistors are no longer being made (or are very expensive), most modern designers have been forced to go to operational amplifiers. Op amps have improved tremendously since the 80's, but may not sound as good as discrete designs, even today.

Coupling caps, if used, will need to be replaced with modern equivalents. Film caps not so much (unless you are talking Mundorf or similar). These have been improved in modern versions a great deal. In older equipment high capacitance polypropylene were almost non-existent, but today can be obtained for reasonable prices (and will fit size wise). In older designs teflon caps were very rare, but can be obtained today.

In digital the newer products have the edge, due obviously to higher IC computing power and VLSI circuitry.