The USB Dual Pre is a full-featured high quality dual portable preamplifier and computer interface packed into a compact rugged case. It is designed to work over a wide variety of applications from remote field recording to desktop/studio tracking. Each of the two low noise input channels has up to 48 dB of clean gain with signal present and clip LED indicators. Inputs can be either XLR balanced or 1/4-inch TRS. Each of the 1/4-inch TRS outputs is buffered low impedance balanced. USB Dual Pre Project Series Applications: USB Dual Pre is powered via the USB bus. Internal 9 Volt battery, or optional external 12V power supply (or any combination of USB, battery & power supply) can be used depending on application. When running powered by battery alone, you should expect in excess of 50 hours of operation with phantom power off. Battery life will drop to approximately 20 hours (depending on microphone) when phantom powering is engaged (still enough time to get through an average session). Built-in low noise +48 Volt phantom power supply allows you to power up to 2 microphones as well as the preamplifier when running from any power sources including the USB bus. 1/8-inch TRS mini headphone jack with level and monitor mix controls on the rear allow for latency free local monitoring of the inputs while recording as well as playback monitoring of the USB bus. monitor mix is also routed to the 1/4-inch TRS balanced outputs. This lets you use the 1/4-inch outputs as either preamplifier outputs or as the monitor feed to your powered monitors. Fully compliant with the USB 1.1 specification and uses USB adaptive mode for playback and USB asynchronous mode for record. Works with the USB audio device drivers built into Windows 98SE/ME/2000/XP/Vista and Apple OS9.1/OSX computers with native USB support No special drivers needed