I have the k-6 that will run from phantom or AA...
as far as concert recording, you want to use phantom, not AA... the higher the voltage, the higher the SPL, and that matters for loud concerts. I have used them with AA's when I had to plug into a camera that didn't have phantom... it works fine for low volume settings, like interviewing someone in a video setting. But for concerts you definitely want the phantom, and make sure its 48v for best performance.
A lot of tapers kind of look down on you for using the ME66's for concert recording, because they were designed for video. I personally love the way they sound (as do many listeners), and they pair beautifully with a V3.
I would highly recommend the purchase.