I actually have that exact set up. Now I've never heard the "NWZ-E344" but I can say the iaudio 9 is the best DAP I've used SQ-wise. And that was before I turned on BBE, (it's switched off default.) Once I started taking advantage of Cowon's EQ, fantastic! That's my opinion on the sound quality, could it get better? My only reference is an S9. Now for facts:
I've heard the S9, and the SQ is indistinguishable compared to the I9. I believe they both also have the same output 29/29 - 16Ω.
The screen scratches very easily in my experience, it's not Gorilla Glass like the S9. So I bought a screen protector on my second one & it's stayed perfectly clean.
The first one kept freezing on me so I had to send it back to JetAudio (I bought it on ebay). To their credit though, they didn't just fix it, they sent me a new one. I suspect that the freezing started because of an OS problem (Mac) rather than a Cowon problem.
Although the second one has been working flawlessly with my Mac.
I'd say the battery life is as claimed (29hrs) because I seem to get around 20-22hrs using BBE permanently & with the screen on full brightness, I also fiddle with it constantly as the music's playing, (a side effect of BBE.)
Everything you have read about the S9's SQ applies to the i9, including the bit about sound being a tad too bright. (If you must find a fault.)
Sounds pretty good with the S4s, but I'd say the S9/i9 deserves better headphones.
Edited by sphinxvc - 9/16/10 at 6:38am
