Regarding the 6+
Its headphone out is the best I've heard on a phone. In fact, it's the first stock jack I consider listenable. I found previous i devices to be best in class, but still lacked the focus of a good dedicated portable DAC. The 6+ doesn't project as deep a soundstage as the Pico, Microstreamer, or DX90. The built in amp doesn't have nearly the sense of slam that the a good portable amp does either. But the proportions are all there. I can't hear any details present in my dedicated portables that are missing from the 6+. The relationship between loud and quiet sounds, the relative spaces between instruments, and the textural clarity are all as accurate as I've heard from a portable. I don't know if they used a new DAC chip, or implemented the same old one better, but the level of performance Apple achieved is game changing. I was going to get a DX90, but now there's really no point. It certainly makes paying the premium on a 128 gig iPhone feel like a better deal. I wonder if the new iPads sound this good?
Regarding the Sony Z3.
I'm generally pleased with it's headphone jack. It might be ok on less efficient portable headphones. But its noise floor is too high for uber sensitive IEMs. That's not necessarily a knock though, as I've never heard anything other than an iPhone that was quiet enough for IEMs, including several of Samsung's Woflson phones. My wife has had her Z3 for several weeks now, and hasn't once experienced overheating. And this is with hours a day spent gaming. Battery life astoundingly good. Even she can get through a day on charge, which is a first for her. The screen is way too blue by default, but Sony lets you tweak the color balance, which is fantastic. I think Sony's industrial design is first rate too.
