You know that thing about how if you put your Ford engine in your Chevy and your Chevy engine in your Ford, they both go better? And use less fuel! So, I removed my KSC75 drivers from their awesome aftermarket Parts Express headband and put them in my Porta Pro headband. Then I put my Porta Pro drivers in my Parts Express headband. They both got better. HD 800? HD 600? HD 650? Suck it up. Me and Stephen Hawking - separated at birth. He did the thinking, I do the drinking. It's a teamwork thing. As Stephen always said: "There is no I in team but there is a U in drunk". The worst (best?) thing about this is that it's true, the PP driver does benefit from a little more air and less clamping force and the KSC driver does benefit from some extra clamping force and maybe from that extra chunk of plastic reflecting sound back from the rear of the driver. Shit, I don't know if I'm listening with KSC Pros or Porta 75s but I like it.