The Tube MP Project Series from ART, is a professional quality audio interface that connects a microphone, instrument or line level signals to a mixer or other audio input as well as a digital audio workstation via a USB interface. The unit uses a high quality 12AX7A tube to add warmth to the source material and is housed in an all-aluminum stackable chassis. It includes precision LED level metering circuitry and is capable of delivering up to 70dB of clean musical gain. USB (Universal Serial Bus) provides quick and easy connection of the microphone preamp to a computer. The unit features a single Type B USB peripheral connector on the rear panel for outputting audio. One of the nice features of USB is its "Hot Swap" capability, allowing the Tube MP to be connected and disconnected without turning the computer off.