When did the Hi-Fi sound mature?

It didn't - it has actually become more immature since the mid 80's. First it started with the "small speaker big sound" and now most Hi-Fi is nothing more than a narrow elegant speaker (made in China) with impressive Boom Boom Tizz (usually with polished metal drivers and phase plugs to make the consumer think "wow technology" versus the tried and true paper/pulp (think "outdated") cones). The reflex port(s) (yes plural as one beer bottle resonance is no longer enough to compete) are unbiquitous as is one note bass.

Not sure who started it but the boombox sound (often supplemented by earth shaking subwoofers) are now demanded by the masses (who are well trained to expect humongous bass and squashed compressed sound): even if it isn't at all musical, it is at least impressive and that's what matters.

Commcat,

While I disagree with you that there was no real progress up to the mid 80's - culminating in digital audio (I actually think there was progress).

I tend to agree with you that music was probably better sounding (on average) in the 50's than the monstrous squashed pop music we get today on boomboxes...however music is widely available and cheap for the masses now so I guess that is a form of improvement (if you can call it that).

Al,

Nice post. It is always pleasant to see a balanced view that does not follow the heavily beaten path of simply pitting digital against analog or tubes against SS!