About the same for me - varies with how loud the track I'm listening to is. Its not as good as my desktop setup, but its definitely decent for a portable one.
M17 is no phone - its no slouch to powering full size headphones.
I donno, maybe an hour or so. Was definitely more of a morbid curiosity thing..
I'm not gonna sit here and tell you the M17 is
the ideal pairing, but it did drive them and the tungstens didn't sound bad off them.
The Holo May + Envy combo was definitely better.
I do have the VC and can try those out to compare it.