Received my HD6XX yesterday. Had a couple of hours listening, here are some fist impressions for those who might consider joining the drop but are still in doubt. As a background: I own several headphones that I know really well: Shure SRH240, Grado SR80e, Sennheiser PX100II, HD518, HD598, AKG K240, Beyerdynamic DT770 250ohm, Audio Technica ATH-M50x, Sony MDR 7506, Koss Porta Pro, Koss KPH 30i. I listened through both a Cambridge Audio...