I'm still living off of my third gen 10 gb iPod, but after thinking about it for a long time, I'm going to go with the iPhone. Apparently etymotic er6i's don't have a problem with the recessed headphone jack on the iPhone, so I'm guessing that the er-4p won't either, although I'm not sure, and haven't found any proof that that's the case as well. It kind of sucks that you have to go through so many steps to get the lineout dock on the iPhone to work properly (not to mention that apparently only the ALO one works), so I'm going to forgo an amp.