Help tuning sound of amp

That was indeed the kind of adaptation I was talking about,

But I also know what you mean because I have become so accustomed to the HD600's early roll off of the bass that I don't like the sound of my HD820 without lowering the bass tone control on my amp by at least 3 dB on most modern (post 1980s) recordings. That difference is too big for my hearing to adapt to.