I am not an expert on the HP2 (I do know them though, although I never owned them), but I have done a lot of experiments with balancing headphones and own(ed) several balanced amps.
In my experience not all headphones benefit equally from balancing, some improve considerably more than others. The HD650 benefits the most of all I have heard, K701 some, K340 not at all, to give some examples I've tried. High impedance headphones seem to benefit more than low impedance headphones. The most benefit is always in tighter bass and improved dynamics, sometimes also better detail and that often results in better soundstage.
Those are not areas that the HP2 needs improvement in my opinion. They are also low impedance headphones.
I think I would not do it personally. I would not expect any worthwhile improvement and besides, I would, like you, hesitate to "maim" a very special one-of-a-kind pair of headphones.