Up for sale is an Eisen designed 500 series mic preamp. This was his Neve-ish model and has a Carnhill 9045-p Input transformer; the modern equivalent of what goes in a 1073 preamp. Op amp is Purple KDJ4. Not sure on the output transformer, but I believe it is a Profile 4804 (which is equivalent to an API 2503). All highly regarded parts and not cheap.
All designs were by Jens Jungkurth of Purple Audio. This is a really great sounding preamp with a big sound; I liked it just as much as my Avedis MA5's and having an xlr input on the front was a nice convenience. The item "Eisen Neve-clone 500 series mic preamp, Carnhill transformer, Purple Opamp" is in sale since Sunday, July 15, 2018.This item is in the category "Musical Instruments & Gear\Pro Audio Equipment\Preamps & Channel Strips". The seller is "zenteraman" and is located in Mattoon, Illinois. This item can be shipped to United States.