@tubetime I had seen some mini tube amplifiers that used tubes around this sort of size range, but they were glass. It's insane seeing all these "nuvistors" made with metal casing. It must handle heat a lot better (though I suppose it also would take longer to heat up sufficiently?) and definitely is tougher and I would imagine would last longer? Now I'm wondering why they didn't do this from the start? Harder to keep gasses from leaking?