Here's the latest DI I was able to build, using a Triad A55J transformer that's in great condition, actually bought this one from a museum.
It's the public domain Ed Wolfrum design/schematic with a variable pad, input/thru jacks, pin 1 ground lift on the XLR. I added a polarity flip for extra convenience.
Hammond enclosure, Alpha potentiometer, heavy duty toggle switches, Neutrik XLR. Build process is focused on durability and sturdiness.
These transformers I use have a somewhat lower input impedance than the A-11J or A12J but they are from the same family, same factory. They also handle higher levels so they're definitely in the "big iron" category of transformers. They are great with passive or active instruments, or line outputs, with an obvious, desirable tonal coloration.
To date I've sold 5 of these to RGO members, a few elsewhere, and the feedback has been very positive.
Price is $299 and the shipping will be free. Paypal payment is preferred.