Download the owner's manual at http://www.adcom.com/ownersmanuals.htm
There are one pair of "bypass" outputs--Direct coupled, and no tone controls. There are two pair of "Main" outputs--Lab and Normal. The Lab outputs are direct coupled, but the tone and high filter can be switched in if desired. The normal outputs are capacitor coupled and the tone and high filters can be switched in if desired.
If you choose to use the tone controls, the preamp will also invert polarity on the "Main" outputs.
There are one pair of "bypass" outputs--Direct coupled, and no tone controls. There are two pair of "Main" outputs--Lab and Normal. The Lab outputs are direct coupled, but the tone and high filter can be switched in if desired. The normal outputs are capacitor coupled and the tone and high filters can be switched in if desired.
If you choose to use the tone controls, the preamp will also invert polarity on the "Main" outputs.