I used small, sticky velcro tabs to attach a HD600 headband pad to my AKG 550's headband. It worked great. Your head shape and milage may vary! (I would recommend the official Sennheiser one - I bought a cheap copy off Amazon and it was too firm.) 

Always seemed odd to me that Beyer have these well balanced cans, like the 150 and 250, that no-ones heard of. The 'Beyer sound', as heard in the 770, 880, 990 and various Tesla models, is so unforgiving and to my ears somewhat unnatural. With headphones like the Nad HP50 and the new Focals...

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I'm afraid I'm not really knowledgable about the demands of mixing and mastering.  In general terms though - flat, analytical, neutral, balanced - these are all are definitions that are seemingly still in flux in the headphone world. This article might help explain why...

Hey - 'Fraid I can't help on the Yamaha side of things but I do have a DT770, 80 ohm and a DT150 to hand. They're both extremely comfortable and robust cans. The aesthetics speak for themselves - you like the utilitarian vibe, or you don't.  Both probably need some decent amping - the 150...