The Hall Research Stereo Audio Ground - Loop Isolator & Filter with RCA Connectors effectively eliminates ground loop noise between audio sources such as DVD players, MP3 players, or notebook PCs and audio equipment. With a frequency response of +.03 dB from 20 Hz to 20 kHz, this isolator uses proprietary audio transformers and filters to completely remove any spurious buzz and hum. Its compact design makes it ideal for use in classrooms, conference rooms, or any AV presentation setting, providing a near - perfect audio experience without interference.