The Shure A15AS Switchable In-Line Attenuator reduces the level of any balanced microphone or line-level signal by 15, 20, or 25 dB. It is specially suited to reducing the level of a high-output microphone to prevent it from overloading the microphone input of a mixer or recorder in applications with high sound pressure levels. In addition, the A15AS may be used to reduce the level of a line-level mixer output to prevent overloading the aux-level input of a recorder.

The A15AS is equipped with a female 3-pin XLR connector on the input side, and a male 3-pin XLR connector on the output side. Attenuation is controlled by a three-position slide switch. The A15AS allows phantom power to pass through from the mixer to the microphone, so it can be used with condenser microphones.