The magic of El Chapultepec is hardly a secret. The small, smoky rectangle of a club has a long history of hosting both local and traveling jazz greats, and owner Jerry Krantz's involvement with and interest in Denver's lively jazz scene is well known. Over the past several years, the Pec's location in the heart of LoDo has pretty much served as a guarantee that the place will be jumpin' no matter what night of the week it is, even if the people clamoring for booths and bar space couldn't tell Thelonious Monk from Mickey Mouse. No matter: Even when relegated to the standing-room-only sections of the bar, a person would be hard-pressed not to feel the energy surging through the place. Whether it rises out of the consistently excellent duos, trios and quartets that grace the stage night after night or expresses itself in the lively exchanges that take place between the folks on the floor, it's there.