I do hear hiss with the TripleFis and my now-departed UM2s on my iPhone, but it's at the same level (if not lower) of the Clip+.
Do you guys have faulty iphone4s? Because every IEM i tried with it (including my ES3X and CK100) I can barely hear any hiss at all even without music playing.
The iPhone 4 sounds truly horrible in most cases - the top end is "tizzy" and there's almost no useful bass end. There is quite a lot of white noise when not playing anything (it's actually really noisy!). In common with EVERY Apple product I've tried (and reviewed), it promises a lot, costs a lot, but delivers very little and very poorly. Get a Galaxy S - it's better in EVERY way!
I've had the iPhone 4 for a week now and I've been noticing that there is a loud hissing sound coming out of the headphone jack. The noise floor is also extremely high with this phone (I suspect its picking up radio interference from the antenna). My 3G was dead quiet compared to the 4 when it was plugged into the car. In fact, I'm thinking of getting rid of this thing. It drops calls when you hold it the wrong way, randomly kicks calls into Facetime or speakerphone, and hisses.
I agree with the noise out of the jack. Using IE7s here. Much much noisier than my Clip+. However it does have pretty good soundstage and detail suprisingly