Just to give an update, I've spent about a month with them and they are still clamping my head pretty well. I tried out the book method to stretch them, but they tend to go back to clamp mode pretty quickly. They sound great with lossless music like from CDs or lossless rips, but they're brutal on lossy MP3s. I now understand the complaints about pops, hiss, and static - I couldn't hear those things very well with my previous headphones or speaker setups. The 650s are very revealing. I ended up purchasing a used Gilmore Lite headphone amp to drive the 650s; it did make a fair amount of difference and I would highly recommend getting a good amp if you are planning on using HD-650s. However, I prefer the lightweight of my 570s and also the portability - they don't require an amp and can be driven directly from my laptop. The sound isn't quite as good as the 650s with a dedicated amp, but I also don't hear all the flaws in my music collection with them. If you decide to purchase the 650s, my vote would go to JR instead of Comp-U-Plus because JR has a better return policy (Comp-U-Plus won't take them back if they've been opened).