Ten thousand people playing ten thousand different instruments at once, badly and joyfully, all day — you hear it before you get through the doors.
Every January, everybody who makes a living from sound converges on Anaheim: guitar builders, synth companies, drum makers, studio electronics, DJ hardware, live sound rigs, recording software, and whatever the newest thing is that nobody has settled on a name for. The floor is genuinely too large to cover in a day, so plan on two.
It is primarily a trade show, which means full access wants professional credentials. But the demos happen in the open, the educational programming is real, and the whole city runs an unofficial second convention after hours — brand showcases, late parties, and acoustic sets in hotel lobbies where somebody you have never heard of quietly destroys the room.
If you play seriously, this is the closest thing your life has to a pilgrimage. Go touch the expensive one.