Yes, I remember the discussion well and had it privately with amb long before that thread when I was thinking of using the JT in my first beta22 (I actually purchased and then sold a JT kit, just ask thrice ). As to how much you can violate the 10x rule and how many SS sources have higher than a 200ohm output impedance I can't say. I do trust amb's opinion on the matter, that's for sure, you don't see a JT in any of my gear do you?