Also forgot there was a HD480 1700ohm impedance version specifically made for the BBC.
Just a guess, i think you prefer the HD480 to the HD570 by a wide margin, correct?
I would keep the HD480, the HD500 and HD570 and HD575 (former HD500) are not good headphones for their original selling prices. They are from the Bionetic series which was not in the same league as the series before (HD265, HD535, 545 and HD565)