Can't help but wonder how the Langevin circuit compares to that of a channel in an Ampex mx-10 i have. I used a couple linked about 50 years ago, and felt so behind-the-times because it wasn't solid state. Eventually got Opamp Labs ( anybody remember that?) and took a while before I realized "thin" did not mean "clean" - which is what transformerless sounds like. Though I sold those a long time ago, eventually found another. As plain vanilla as vanilla gets in features, but tubes, transformers, etc. Never been around Langevin. Several Houston studios from the 60's used mx10's as well, going into state-of-the-art Ampex 3 trackers.