Yeasayer
Before: Strange world music-influenced eclecticism
After: Identikit Brooklyn “hey, look, we have synths!” stuff
Depeche Mode
Before: Slap-happy, mildly camp synthpop
After: Portentous stadium rock
Pink Floyd
Before: Winsome psychedelic noodlings
After: Portentous stadium rock
The Horrors
Before: Misfits cover band
After: Shoegaze devotees
Radiohead
Before: Best guitar band of the ’90s
After: Warp devotees
M83
Before: Freeform pysch extravaganzas and ambient excursions
After: Pitchfork pop
The Clash
Before: Angry left-wing punks
After: Angry left-wing musical visionaries
Best Coast
Before: Most excellent psych weirdness
After: Sub-girl group Cali tedium
Robyn
Before: Cheesy pop and child stardom
After: Hyper-cool electropop and angular haircuts
Nick Cave
Before: The Devil incarnate
After: Suit-wearing piano balladeer
Who I like both “before” and “after”: Nick Cave, Radiohead and The Clash.
Who I like “after”: Depeche Mode and Pink Floyd (does that make me portentous?)
Should probably check the others out some time.
Obvious (big name) omissions include: The Beatles, U2, Neil Young, Pearl Jam, Sting/The Police.