Man, I'm so bummed out that I forgot to listen to Frank's 507 at the NorCal meet. People were saying it had a lot more bass impact than the previous Lambdas. Actually, I ran over to Frank's rig to try to listen to it but he was already packing, so I put them on just to see how the new arc assembly fit me. It was a considerably tighter fit than the older arc assemblies. I'm guessing that since it seems to seal the ears better now, that helps out with the bass (see the FR plots of a Lambda properly fitted vs a Lambda with a bad seal between the ear and driver). Well, that and the stiffer mounting scheme. Do you think there's any truth to this or am I being 'Ed'-ish?