I currently have the beautiful and awesome Sennheiser HD 598s. I've had them for about 2 weeks, and really love them, but my main complaint is they are a little bass light and they leak a ton. The leaking is not really an issue for me, but I am a little disappointed the the bass not being strong. It's not weak or anything, and the headphones are loud. I use them on my macbook pro and iPhone. The volume is good. What's really great about these headphones is the soundstage, mids, highs, and clarity. I basically want these same headphones with a little more punch in the bottom end. That's why I'm considering either of the Beyerdynamic's: either the DT 770 80ohm, or Custom One Pro (COP). The HD598 and super comfortable, and I think probably one of the coolest looking headphone out there. Call me shallow, but the look is a little in keeping me from returning them. That said, I'm willing to sacrafice a little of nearly perfect crystal clear mids, highs and soundstage for a little more thump and bottom end. I listen to Jazz, Metal, Indy Rock, and some classical and techno or rap. I'm wondering if the COP bass switch is really worth it, or is it a gimmick? For instance, could I switch it when listening from Dexter Gordon (Jazz), to Inflames (Metal), to Wilco (Indy), to Bach's awesome cello pieces? I'm leaning towards the DT 770 80 ohm's. Am I wrong. Thanks!