cheapest speaker made in the last 10 year that can beat any speaker made before 1970?

Speakers don't get tenure ... 😉

but it is technology, isn' it? like computer, right? no?

but it is technology, isn’ it? like computer, right? no?

Physics are a huge part of speaker design and function, and that has not evolved.

The technology has evolved, but there haven’t been many "breakthrough" advancements that changed the game dramatically. It’s more like many marketable baby steps. Emphasis on "marketable", because in many cases, sales and profit trump sound improvement. The majority of speakers are profit boxes that typically don’t represent state of the art from their era.

I’d be surprised if there weren’t several great speakers from the 60’s and 70s that wouldn’t raise an eyebrow or two (assuming any age-related degradation was addressed)

Does that include speakers I would buy at Walmart for $39?

In my opinion, can't be done.  Once you get into "hi-fi", too much comes down to taste.  My speakers were built in 1958 and sound better than most of what I have ever heard, at least to me.  Then you get into age of design verses manufacture date.  I do like the sound of a Tannoy Westminster, but that is actually old tech.  I was just at a store in California last week and listened to the Wilson top of the line, driven by the top of the line D'Agostino amps.  Yep, everything was there and better just comes down to taste.  It could definitely get louder than what I have.  I walked away knowing that I like what I have better.  They also had some Boenicke speakers that, for the money, were much more toe curling for me than the Wilson.  From there you also have some unbelievable "other" items to beat if you are going after everything pre-1970.  Take a tour of Oswalds Mill or listen to some ginourmous old Western Electrics.