I have the same combo! I've had them for about the same amount of time as you, and they're still in great shape.
I originally only bought the e10k because my former PC's audio output were prone to interference, but I still love having the external DAC/amp.
Just ordered a pair of HD6XXs from Massdrop, can't wait to give them a shot.
Definitely not. They're fairly neutral which I like, but isn't what you seem to be looking for. Being open-backed certainly doesn't help.