I got a pair yesterday from Razordog. FYI, the $50 off coupon is not good on KEF, so the price of $299 is the same as anyone that is selling them in the States, but they do have free delivery and shipped quickly via Priority mail. My main reference is the Etyomic ER4P/S as I've had my pair for years. I lean towards flat response so obviously the reviews earlier in this thread got my attention, as well as the original picture that appeared on the front page. First the look and feel - nice, quality finish, not as heavy as they look, but definitely well put together. Pressure for my head is just right, quick movements might dislodge them but for normal movements and comfort the clamp is just right to me. Enough to offer some solitude from outside noise but I believe loose enough for extended wearing. Time will tell as I've only worn them an hour here and there. Too many meetings today to wear non stop. Sound - First impressions are more bass than the ER4P, voices stand out more and are very clear, and overall the music seems more alive and more energetic. I agee with the other reviews that talk about the voices seem to be right in the room with you. Hard for me to describe in technical terms. Live music is more fun to listen to on these as well. Pianos sound right, female voices are what I expect, sound stage is smaller than full size headphones but on par or bigger than IEMs. These compare very well to the ER4S which I do feel is a step above the ER4P. Other comparisons - T1 - smaller sound stage, a little more bass, clarity about the same, more edge/punch, less "Refined" sound, but definitely much closer than $300 to $1300 headphones should be. The T1 is the better headphone but not $1000 better. Momentum - If you like the Momentum you probably aren't going to like these. Less bass, mids to me are more clear, highs are a little more pronounced, and comfort is much better. My ears didn't fit the Momentum at all. It comes down to clarity vs. the Senn sound to me. AKG K702 anniversary edition - More bass but pretty close across the spectrum. Smaller sound stage. The anniversary edition, with no bumps in the headband, are hands down the most comfortable headphone I've ever worn. HE-500 - much more comfortable, a tad brighter but the overall sound is pretty close. Disclaimer, it's been a while since I had the He-500 so going from memory here. HE-500 sounded more full/smooth where the M500 has a little more edge/sparkle. W3000anv - Again , it's been a while since I had these but the M500 isn't as colorful as the W3000, more edge/aggressive and not as delicate/muscial, comfort is a tie, the wing approach on the W3000 worked for me, others maybe not. The W3000 had a more refined sound as well. This is one man's opinion and I sure don't have golden ears, I just know what I like. Hope this helps someone else decide if the M500 is for you.