ART Cleanbox II Hum Eliminator. 

“Hum” in an audio system is often caused by loop effects which act like antennas. These loops can easily pick up a 60 Hz (or higher harmonics) hum transmitted by electrical wiring. Typically, these loops are connected via grounds, more commonly called “ground loops”. The safest way to eliminate unwanted noise is with the CleanBOX II.

Features

• Eliminates “ground loops”
• 2x 1/4" inputs and outputs
• Rugged housing