Germanium Drive controls the input gain of the Germanium amp. Feedback Control to adjust the amount of signal fed from the amplifier output back to the input.This is awesome, unfortunately due to financial necessities... Germanium knife cutting drive for guitars and synths in the DI, vocal and cab miking foreground in the XLR (that's how I use it). Power supply included, it powers two Chandler units if needed. Unit is used but guaranteed to be in working condition. The item "Chandler Limited Germanium Preamp/DI Microphone Preamp with Power Supply" is in sale since Monday, April 19, 2021. This item is in the category "Musical Instruments & Gear\Pro Audio Equipment\Preamps & Channel Strips". The seller is "orpheusmaximo2" and is located in Las Vegas, Nevada. This item can be shipped worldwide.