Speaker volume controls are used to aid in balancing speakers. These are most commonly used with home entertainment systems that are custom-built to match irregular room shapes. Every room has unique harmonics, so the same speakers in two different rooms will sound differently. Speaker volume control resistors are used to help custom set each speaker to match a room’s unique harmonics. The sound level from each speaker should be equal at the central listening point.

How to Select the Correct Rheostat for a Speaker Volume Control - 58