I have a pair of Sennheiser HD580s and a nice headphone amp that I listen to pretty much every night before bed. A bit more laid back than the M3s, but still very well balanced and detailed. I've occasionally wanted to get some more up front headphones and I have tried a few others, but suffice it to say I've never once considered selling the 580s - they have a few minor shortcomings but all in all are extremely good at what they do. I actually listen to them much more than I listen to my speakers. That probably wouldn't be the case if I wasn't sharing the house with 2 other people, though.
