When athletic height jumping was considered done and perfected, there was the Fosbury flop which opened new possibilities. Do you think there was such a moment in the music history? When someone showed how things can be done and from there everyone is using his/her technique?
Equal temperament, where all the keys have basically the same intervals rather than having different characters as in just intonation. Enabled modulation from one key to another as in Bach and Jazz.
A few modern production techniques come close, but I agree, equal temperament tuning was a game changer. It allowed "anyone" to transpose "any" piece of music into "any" key, broadening the available instruments for a piece.
Plus drop D tuning would be impossible without it.
Dave Davies of The Kinks changed rock music with a razor blade. Distortion pedals existed but they couldn't provide the same kind of fuss sound that we hear in "You Really Got Me"... but a year later they could.
So many great examples in this thread already, so I'm going to go with a simpler one: Guitar overdrive. intentionally increasing the gain beyond max input level of the amplifier to produce a more square wave tone would've seemed sacrilege to guitarists from the 30's and 40's.
And today it's the foundation of so many guitar sounds and music genres.The I–V–vi–IV progression
https://en.m.wikipedia.org/wiki/I%E2%80%93V%E2%80%93vi%E2%80%93IV_progression
I would say going from analogue to digital recording. Digital made edits possible that where impossible before.
i think getting any kind of reliable recording was a bigger jump. it totally transformed the way we listen to music.
the other thing is microphones and speakers. changed live music totally.
Not just one imho: if we go that back in time I'd start with electric instruments, more recently (~50 yrs ago) multitrack, then electronic music (whether you have it started with synth in the 80s or with music entirely made on a computer in the early 00s). All 3 changed the game and were adopted by everyone
