I sent them an email, that is their direct site. I'm going to order a JS-6123HS since I can try it in my 300B, 2A3, and EL84 amps, I'll run THD scans with my HP8903B and posts the results. I know that El Paso Tube amps on YouTube made a video of one of their Push Pull outputs and it performed beautifully, I'm curious to see if their single ended outputs do just as well.