Chelcie ParryYou know a piece of theater has done something right when, many days later, it is still provoking pin-pricks of intrigue, revelation, and mystery in one’s mind. And so it is with Stereophonic (Playwrights Horizons, to Nov. 26)—one of the most original, stunningly designed, and technically dazzling plays in New York right now. Stereophonic is a must-experience, rather than simply a must-see.This isn’t to say Daniel Adjmi’s play will be for everyone. It is very long, at over three hou