I bought this direct from Raven Labs years ago thinking I would need it but that need never materialized. It has never been used other than to test it. Everything works and it is clean and quiet. If you're looking, you probably know all about this unit, but if you're interested, here are the particulars: Includes: Raven Labs MDB-1 2 Raven Labs power supplies. Original Box All original documentation Front Panel Features: 3 independent 1/4" inputs, one stereo input. THe stereo input utilizes channel 1 (tip) and channel 2 (ring). Volume control and in/out switch for each channel Auxiliary Blend control that allows the user to mix an effect (or another MDB-1) with the original signal. The blend circuit is on a "side chain", helping to maintain signal intefrity and clarity. Mute button with red LED indicator. Kills the signal going to the XLR and line out on the back panel. The Auxiliary send jack is not affected. This allows the user to tune up-with a tuner connected-without sending the signal to a mixing board or amplifier. Power on/off switch with accompanying green LED Rear Panel Features: Line Out. Use this jack to send a signal to an amplifier or any unbalanced input. Auxiliary Send. Use this feature to send a signal to an effect or tuner. By using a "Y" cord, you can send a signal to more than one input. Auxiliary In. Use this feature as a "return" jack from an effect, or mix in any mono external source via the Auxilary Blend control on the front panel. Ground lift for the balanced XLR connector. Balanced XLR jack. Dual 9 volt battery holder. The "drawers" pull out for easy battery insertion/replacement. The MDB-1 is a combination mixer/direct box/buffer/preamp in one small unit 6.7" wide x 1.75" high x 6" deep, and weighs about 2 lbs. The MDB-1 boasts an incredible 10 Meg ohm input impedance making it the perfect buffer for any instrument. Coupled with super low noise (-105dB typical), distortion (0.005% @ 1KHz) and a frequency response from 10Hz to 60 KHz, makes this one of the finest pieces of equipment in its category. Input headroom is 2 volts RMS. Maximum gain is 3X with "unity" being at 12 o'clock on the volume control. Two nine volt batteries are used in a +/- arrangement eliminating the need for multiple coupling capacitors that can "color" the sound. Battery life in field tests has been around 100 hours. This unique design will function down to +/- 3 volts. **It should be noted that the power connector is a tip/ring/sleeve configuration and the power supply MUST be connected to the MDB-1 before plugging into the outlet. US Domestic shipping only Feel free to ask questions.