I don't know really. Anything's possible, but the HE-400 will sound pretty good just out of an iPod.
I've not heard those JH16's, but they sound like some kind of extremely potent headphone if their bass is that powerful. The HE-400 has one of the hardest hitting basses you'll find in an open headphone.
out of an ipod? I think my c5 amp is at least more powerful than that. JH16's are the only ear toys I've had that could combine clarity, detail, and insane bass at the same time, and do it well. The he-400 is not bad by comparison, just a bit different but I expected that. My only question to the hifi pro/gods/gurus is 'is the fiio e12 powerful enough to drive the he-400 to YOUR satisfaction?' I hope some headphone-supremus can answer this.