The OCSD is an all analog, tweakable Cabinet Simulator with DI out and integrated headphone amp. This one is VERY popular among metal bass players, because of the way they can tune the perfect high end cut needed for softening those nasty harmonics, and dialing the perfect low end response that will match the instrument and the FOH cabinet response. Is a very, very powerful tool for live use and recording. It has helped a lot of working musicians to leave the amp at home and just go happy with their bass and pedalboard..