LeBron James -- SIZE MATTERS ... And I Like My Headphones Tiny

Lebron James has a message for guys like Richard Sherman and Colin Kaepernick ... when it comes to the post-game music jam, big is out ... small is in.

James was rockin' his new Beats by Dre "Powerbeats" headphones after the Cavs beat up on the Knicks in NYC last night.

They're tiny. They're wireless ... and it's a huge fashion change from the classic Beats by Dre headphones which are intentionally bulky and have become a fashion staple for tons of athletes.

James is a trendsetter -- so if he goes small ... does it mean the reign of the bulky headphones are over?