Boston Acoustics A400 - a forgotten classic.
Fact is, many flagship speakers of days gone by, have been forgotten now, but a really good speaker (and flagship speakers are almost invariably VERY good), remains a really good speaker....
Sure there has been progress... the best of the mass market is now better than it was 50 years ago.... the average level of quality has risen substantially, and DSP with Active speakers has shifted what can be achieved at certain pricepoints... but premium speakers were never so cost constrained.
A refurbished Boston A400, would I believe, given any speakers under $10k a run for their money...
Like any speaker comparison, each individual design is a different compromise of strengths and weaknesses... we have yet to see a "perfect" speaker for all circumstances....
Another great speaker - the Revox Agora B - a powered/active speaker from the 1980's - presaging the change that ultimately happened in the 21st century - the move to active speakers... but this was 25 to 35 years earlier!
The Quad electrostatics are still around today, and still highly regarded, still many don't realise that you can often pick up a set of 50 year old ESL63's or ESL57's for very low $... (like any used purchase, check if they have been refurbed, or need refurbing, and check cost of refurb... but typically you can get a set of ESL63's in fully refurbed state for circa 1/10th the price of their current equivalent - and they provide 99% of the performance of the current model!!)
Other classics of yesteryear, where bargains can oft be found as they are forgotten ... Klipsch Klipschorns, La Scala's, Forte's - all of these can be refurbed or updated to current spec, and there are 50 year old (or older) sets of these floating around.
There are loads of excellent speakers from the 70's and 80's... but you do need to know what to search for... the hardest part might be getting an education into the speakers of 50 years ago.
