Let it be known that the LG V10 can drive the HD650 hahaha. It's nothing compared to my desktop but I am nowhere near the max volume and I'm getting plenty of sound! I can confirm though that the V10 -> Q701 sounds great to my ears.
That is very interesting that one sounded so much different than the other. Maybe one was defective? If you get your new one, I'd try and test their frequency response if you can find someone with the equipment.
Haha that's the problem! I wear headphones all day if I'm at my PC and then I put on the 650 and forget. I'm not the type who complains about the weight of planars but I definitely know I'm wearing headphones. The 650 is just too comphy. Also my mic won't fit on the LCD-2's cable.