That's somewhat strange. I guess with or without Rockbox should not make a difference hiss-wise? Do you have a FiiO X3 or a Cowon iaudio 9 so that you could check on these? kind regards

I tried an Ipod and also the Fiio X3 - the hiss was audible with both of them and really annoying on quiet tracks. I think ill have to go for other IEM after all :(. Nevertheless thank you for your help.

Thank you for your answer. Buying new IEM is no option as i can't return the Hippo's (and i actually don't wan't to). What is bothering me is that the output impedance of the iaudio9 is about 1.5 ohms and the one of the load 16 ohms - so there should be no mismatch in my understanding...

Hello everybody,     Recently, my SoundMagic E10 Headphones died. Having read many great thinks about Jaben i decided to buy a new pair there, feeling adventurous i picked the Hippo Pro One (single Balance Armature). Beside sounding great in my opinion, the first thing i noticed was a...