The ST-MX3 3-Channel Line Input/Output Audio Mixer from RDL is a line-level mixer module that provides audio mixing of three line-level inputs with individual input gain adjustments. It can be used for fixed installation in commercial offices, retail stores, schools, medical offices, and general sound reinforcement applications. 

The three inputs are summed to a single output that is capable of balanced or unbalanced signals. The ST-MX3 features dual-LED output meters and audio-taper, single-turn gain-adjustment dials for each input. Interlocking-adhesive mounting tabs are included. A 24 VDC (PS-24AS, USA) power supply (available separately) is required.