Yes. I believe that either the LCD-2 or 3 have been used as test headphones.
And since this isn't the HE-6 appreciation thread and I less likely to get crucified here, the HE-6 would probably sound good out of this as well. While I am sure I wasn't "maximizing" the potential of the HE-6, I was able to get enjoyable sound out of my Nuforce HDP which maxes out at 200 something mW into low impedance headphones. This is designed to have much more power on tap, plus tone shaping, so the HE-6 would probably sound quite good out of this device.