[CyberCowboy777]

Cultural maybe, but I am not so sure about musical.

They were accessible and along with many others found foundation within blues, gospel and early rock.

But they did not anymore greatly expand the horizons of music.

[Hemingway's Ghost]

But they did not anymore greatly expand the horizons of music.

No, they just pioneered about a thousand studio techniques and introduced a bunch of non-traditional instruments (sitar) and arrangements into popular music, that's all. Before "I Feel Fine," feedback even rarely made its way into finished products.

Ever hear the tune "Tommorrow Never Knows"? That came out in '66, and it still sounds current.