A little of both Bubba. Some from stuff I've bought because it was a bargain at the time, some given to me or the owner of one sends it to me. Nothing secretive here. If you supply the unit for conversion 500-800 depending on how far you want to go. If I supply the donor unit , that plus what I have in it.
These amps , after the White Oak upgrades are WORLD class in certain specifications. The SNR on the fully comp 400 here is 107.2DB UNWEIGHTED, A weighted IEC I suspect will be way close 120db, simply fantastic stuff. These amps lasted 40 years and longer with cheesy PCB's and poor wire management, Joe's state of the art PCB's and other improvements will take them even longer into the future. My son's grandson will be listening to the amp great-great grandpa laatsch55 built back in '14.