I'm selling a pair of the greatest input transformers ever to be fabricated: the Peerless K-241D.These are a true holy grail input transformer for mic and line input into typically tube circuitry preamps.These are in excellent condition and both check out functionally.I hooked them up feeding a line a level signal and flipping the polarity of one to check for stereo compatibility. They are very well matched and would make a great stereo preamp for anything from a mic to a phono preamp.The renowned equipment designer and audiophile George Massenburg mentioned that he built a tube preamp with a Peerless K241D transformer, and the audio sounded like the voice of God... These are extremely rare and do not come up for auction very often. Let me know if perhaps you would like to purchase only one or have any other questions.Thanks for looking and check out my other vintage audio gear.