ART Pro Audio PDB Passive Direct BoxThe PDB is a passive direct box for connecting unbalanced instrument, line, or speaker signals to balanced inputs. The input signal is sent to a transformer isolated XLR output and a parallel Thru jack, so it can simultaneously be connected to an amplifier on stage. A switchable ground lift helps to eliminate hum, and switchable attenuation offers up to 40 dB of gain reduction. As a fully passive design, the PDB doesnt require an external power