The bathroom manufacturer Duravit launched its DuraStyle and Happy D.2 collections this summer in North America, and now the German brand is making a number of whirlpool-bath technologies available for models in both of those lines. The sleek bathtubs can be outfitted with heaters, waterproof speakers, floating remote controls, LED lights in various colors, and massage jets. The company also has added a new tub with a built-in acrylic headrest to its popular Starck 2 collection (the designer Philippe Starck cr…