original api 312 card (hunttington/ap2622/ap2503), adapted beautifully to api 500 series format by jens eisen (eisen audio). compatible 500 series preamp (authentic 312 configuration) with all api 512 features: gain pot (vintage api knob), 48v switch, -20db pad switch, Ø polarity switch, hi-z 1/4" input, mic input front and rear. looks incredible, sounds incredible (not even similar to 512). pictures from the guts pm me. 1300 euro. bae - 500 lunchbox: 6 way lunchbox w/psu/48v (the only one avalaible which fits the vintage api 550's trouble free) used but in very good shape. 350 euro . 1600 euro all.