As humans (we're all humans here, right??), our capacity to hear has certain limitations that cannot be overcome. The DIY-ers know this. The savvy vintage crowd knows this. The moron who buys the 5 figure price tag, 50kg+ turntable from the fancy store with shiny displays does not know this (*cough*Clearaudio*cough*).
There is a reason why the audio industry fears public ABX testing: in most areas of high fidelity audio reproduction (but not all), by the early 80s you're getting at or very close to the limits of human hearing, and its capacity to resolve the fidelity of audio reproduction.
I would argue that the list of vintage gear that still competes is a very long one. Some of it can be purchased very cheaply. If you are willing to blend old, new, pro and DIY gear, you can get cost-no-object performance for well under 10k USD. Personally, for my main stereo listening, I find I'm pretty damn close these days at a whopping price tag of what would be about 1500-1600 USD. Mind you, I buy second hand, and below market rate at that!
Go to any major high-end, cost-no-object audio store with a trade-in section. Go to their main listening room. Now they might have a set of very, very fine vintage speakers (particularly electrostatic or planar speakers) that have come in via trade-in. Maybe we're looking at a price tag of 2k-5k if the store is interested in offering fair market value used gear. Chances are, they're off to the side on the showroom floor, not plugged into anything. Maybe there's a little system going, but that's risky for the store. Above all, they wouldn't dare put those speakers in the main system room. It could mean ruin. As a buyer interested in the best of the best, why spend 50k when you can spend 2-5, and get something that's the same or better? Yes, better!
Let's think about what would happen if the retailers of modern cost-no-object gear put the finest vintage gear into the mix, side by side. The distributors of the new gear would get angry. The store would take a huge hit financially, even if their margins on trade-ins were decent. Some customers would turn away straight away and head right for the main second-hand market.
Areas in which modern gear has a distinct advantage that's potentially rather audible in an ABX context (let's say 1990 and beyond here):
--Floorstanding speaker performance below ~30hz (i.e. not particularly relevant for the vast majority of music listening).
--Bookshelf speaker performance below ~50hz.
--Subwoofers.
--Digital signal processing, and the corrective opportunities that it offers.
--AD / DA ICs themselves, which can yield excellent results when utilised in modified vintage pro DA & AD Converters / DATs
EDIT: I'll chuck digital audio playback and formats in there, though really 16bit 44.1khz is all you need, CD transport or lossless/FLAC. CD transports were rather sorted by the mid-90s.
I may have missed a thing or two overall, but for music listening that's about it. Yikes, long list!
If you're looking to buy: there's plenty of amazing gear from the 80s and 90s that goes for absolute peanuts. Happy to share my own set-up and make recommendations if there's interest.