Definitely get the E5, I get slight hiss with the E3, but none with the E5, with the added advantage of built in rechargeable battery and volume control, the E5 is superior to the E3.
Have you compared the fiio E3 to fiio E5 ? I'm looking for something for an 1000He (netbook) to boost volume a little with headphones. Mostly for watching movies and listening to conference calls but I'm not a big fan of hiss. Trying to decide between E3, E5 or one of the more expensive DAC solutions. Thanks