My method to find out which direction the fuse should go is to use a mains tester on the fuse holder without the fuse in place. (when possible)
I place the fuse arrow from the hot to the neutral.
Anyone has further comparisons between QSA Yellow and SR Purple?
I have two QSA Yellow (one on a farad lpsu and one on a switch) and contemplating deploying two more, either yellow or sr purple - on my dac and my integrated.