For those of you who are reporting (getting or not getting) hiss, maybe it's worthy to state with which headphones. Also searching for the word "hiss" on this thread, @kdailan's case isn't unique (esp with the TG!334). Still sending it back to have it checked is not a bad idea.
Mone was with the se846. I know its a sensitive iem that picks up hiss when most others dont. My A12 wont though, not noticeable at least.