The FP22 Stereo + 1 Headphone Amplifier provides professional quality stereo headphone monitoring and is ideal for field production, studio recording, and troubleshooting applications. The FP22 is powered by one 9 V battery. With 81 dB of gain, the FP22 can monitor a wide range of signal sources in many different configurations. The FP22 has loop through input circuitry to monitor a signal without affecting the original signal source, balanced XLR connectors (accepts mic or line level), two pairs of headphone outputs, red Power On LED, a removable belt clip and two stereo 1/4-inch loop through jacks.