Im not a pre amp guy but I got an Advanced Audio Design pre-amp,in a trade.It is model 101B.It is rackmountable(one space).Made in Eugene Oregon.I believe it to be mid seventies to early eighties. I seem to remember this company morphing into another company.Can anybody help me use it properly?Even a basic pre-amp 'How too" would help. It has on the front-from left to right- Pre1,pre2,master,then two boost toggles-one labelled gain and the next labelled Hi.Then a Low knob with a toggle labelled150(up) and 75(down).A mid knob with a toggle1K(up)500(down).Then a high knob with a toggle3K(up)2K(down). the back has a High level knob with the "Bi amp outputs" high and low.Then a jack marked "Output line level"and a three pronged female jack. Any help with this is greatly appreciated.Thanks.