Ok, this is my second Amp9 and I am still plagued by this problem. The first time, I got 2 of the 2N7000 transistors for U4/U5, put them in along with R14, R15 and R12. I wasn't sure why R12 should go in, but it was listed in the BOM and I had 3 of the 2.2K resistors.

Anyway, fast-forward to now, the amp blew for unknown reasons (worked fine for a while, then as I was changing inputs, and unmuted, blam!), but now I'm building a second and this time I have an extra 2N7000, the third 2.2k resistor and a third, unknown resistor that is 55.7K?? And, there's this ominous R13 on my board which is not even anywhere in the intructions.

Anyway, I'm guessing all of those parts shouldn't be in there since they appear to drive the fault LED, which is listed as "not used" in the instructions. Right?