Mono Passive Direct Box. Samson's MD1 Mono Passive Direct Box combines premium sound circuitry with durable, roadworthy construction, providing high-quality signal connection solutions for a variety of live sound and recording applications. The MD1 allows clean, balanced lines to be sent from an unbalanced line or instrument signal to a microphone level balanced input. Features include:; All-metal, impact resistant design; Samson STL transformer; Ground Lift switch; 1/4"; Input and Thru; Balanced XLR output; No Phantom or Battery power required