Those who despise discordance would be wise to stick to Guitar Center's acoustic room, where the quiet people dwell among the mandolins. Out on the main floor, a dizzying number of guitars and amplifiers are available for the strumming, squealing and soloing pleasures of aspiring wankers from all walks of life. Go on, grab that Gibson and plug away. Instruments are for playing, and no one's going to stop you from trying out whatever ax strikes your fancy. Just remember some simple etiquette -- speed metal is okay, but "Stairway" is verboten -- and you and the Guitar Center staff will get along just fine. As George Harrison once said, "Don't want no wah-wah."