nothing strange here my friend, as I've explained on the f886 thread, you need both to have an extremely sensitive IEM and to listen to music at pretty low volume.
when I'm out it's no problem obviously, but when I'm alone in a silent place, I tend to go lower and lower in volume over time. as the noise level stays put, when lowering the music volume I reduce the range between the 2 and end up hearing noise.
it's nothing magical, and not even that much of a problem as the simple solution is to add an amp so the ratio music/noise of the dap itself gets maximal.
I'm asking because if the zx1 doesn't have the small "tac" noise every 2 seconds, then I'll get one. but if it's like the f886 then I'll go seek a fitting amp instead and be done with it.
but it's important for me not to buy another dap that might not solve my problem.
go check shigzeo's reviews, he's like me on the subject of hiss and will complain on pretty much all existing daps.
but hiss is something pretty constant that your brain can forget (think dithering). here this "tac" can't be dealt with by my brain and any calm part of a music would let me hear it. I happen to be insistent because it really matters to me to get a clear answer, if I didn't like sony I wouldn't bother trying to find "the one for me". and I believe AnakChan has the sensitive 334, thus my question to him.
I tried to contact sony but at the moment all I had was a guy asking me for a proof of purchase ... and they still haven't answered my angered and detailed reply 3 days ago ^_^.