The Model A15RF In-Line RF Attenuator provides all types of balanced audio systems with greatly improved immunity to radio frequency interference (RFI). It is especially useful in applications where balanced audio devices near strong RFI sources, such as AM radio stations, are connected by long cable runs. The A15RF will not degrade system sound quality or alter system frequency response. In cases where interference is present but not audible, the A15RF can improve perceived sound quality by removing low level interference components from the audio signal path. It passes phantom power and is transparent to differential audio signals ranging from DC to 2 GHz. The A15RF is a passive device and will not damage other equipment. It does not present any additional load to the signal sources, and can be used with phantom-powered mic-level or line-level devices.