I think the best assessment between the older K701/K702 and K712/Annie is not that the newer ones does more better (As in detail, resolution, etc.) but that they do less wrong IMO. The older phones are immensely capable in some areas but also have some deep, stinging flaws; whereas the newer ones are more balanced overall and less frustrating than the older ones, without losing the trademark detail, resolution, and soundstage. It is still slightly limited at high listening levels due to low power handling, but this is slightly offset by the increase in efficiency so it's less of a problem.
I find the K712 to still scale well with better gear like the older ones also. As mentioned earlier, they still do benefit from a solidly powerful amp. But they should still fit better with something like a Magni or O2 than the Older 7 series would. I'd be especially curious of the Vali with it for a budget setup, judging from some of the impressions I've read.
Originally Posted by grizzlybeast View Post
I heard these were hard to power but they are 62 ohms, a lot easier than an hd650 which is 300 ohms
It depends. Technically, 300 ohms requires less current to drive and only needs more voltage gain so they are easily driven by OTL tubes and amps will smaller spec power supplies that can't supply the current to double down power into lower impedances given the voltage. Given a theoretically "perfect" current source, then only the voltage would determine the power. However, larger power supplies to deliver more clean current are typically more expensive to build.
Edited by JWahl - 1/13/14 at 2:30pm