DS Audio is a Japanese maker of optical phono cartridges. Instead of magnets and coils, its designs read the groove with light, using LEDs and photo-detectors. Some models give each channel its own LED and photo-detector, plus a beryllium shading plate. The cartridges work with DS Audio's own equalizers, which take the place of a phono stage. Cantilevers go from aluminum and boron up to diamond, including a one-piece diamond cantilever with the stylus tip built in. Some equalizers offer balanced outputs and selectable low-frequency settings, so owners can match them to their systems.