Hi, I’m still wondering about this. With a 1kOhm resistor the current through the IN-18’s would be 0.18A which is a lot higher than the rated current of 0.008A (MAX) I think the software is switching the tubes on and off at around 333Hz – is this correct? Does this switching mean a higher current is ok? Could you please provide links to the theory behind this and the calculations for current.