BOSS BX-400 4ch Analog Mixer (Junk) Manufacturer / Model Number BOSS (Roland) / BX-400 Product Description This is a BOSS vintage 4-channel analog mixer, the "BX-400". It's a compact mixer made in the 80s, popular for home recording, lo-fi applications, and as a collector's item. This listing is for the main unit only; no case is included. The exterior shows signs of wear and tear, such as scratches and dirt, due to age (see photos).