I have almost bought a GFA-535 so many times over the last few months.
I think it will really be fun as we get more speaker amps both new and old tested. It is the go-to response in many areas that when someone asks about a new amp people tell them to buy vintage because 'you get so much more for your money'. It is great to get actual tests on them so we know if the legendary components really stand up to the new ones. Or if for a hundred or two more could you get a new amp with a warranty and all new components that would perform better.
I guess it depends on what it is and what you are testing.
For example, pure power amps from the past can, I suspect, hold their own against new comparable ones. Because they are discounted so much, it is often cheaper to get them upgraded (there are specialists that do this for the classic brands) with new caps, solders strengthened etc. In that niche, I do agree with “getting more for the money”. Adcom GFA 545 is still a great buy when you find one that is in a decent condition even if you were to get a overhaul. Comparable ones will cost several times more. But buying vintage equipment is not always a connect and forget affair and can be like buying a vintage car.
But it gets much more complicated when you extend beyond power amps to pre-stages, DACs and decoders.
What the new ones can give you is all the advantages of newer technology, not just new components inside. Latest HDMI versions, more decoders, cleaner DACs, connectivity, etc. So the feature set becomes a deciding factor rather than the absolute quality of the sound.
Unfortunately, mid-tier these days is either mass-market kitchen sink devices marketed for features or bare minimum stereo equipment that is difficult to integrate into modern ecosystem of a/v content consumption without spending a lot more.
A few do standout with exceptional balance of features and quality like the NAD T 758 v3 without breaking the bank. Would love to see something like that tested - of things that you can get new these days. Especially if it can be compared to things that cost twice as much or more. Are the latter really built to higher standards and meet higher bars in results if features were similar or satisfied the minimum needs?