Hiss: E7 > E6 > A10 > PA2V2.
While PA2V2 might have the least hiss, it also has the least performance among the 4.
Also saw your question on other threads - sibilance is mainly an issue of the headphone, especially peaks in the frequency response around 2kHz ~ 8kHz. If you want less sibilance, try EQing that section of the FR down. Amp is really not the answer for sibilance.
Wait hiss is sibilance right? if so how would the E11 fit in with those amps. I found a great deal on them, so far seems the most likely candidate, it will be paired with an iphone 3gs, and soon iphone 4. I will use it on my computer, but I don't need a DAC I only have like 3 flac albums, and not all my songs are 320, like half. Also what else does the DAC purpose serve, rather than on the computer?