I think they compliment each other very well. I've had my HE-500s for some time so that's why they don't see much use. I am definitely NOT going to sell them. The HE-500s do everything very well...everything is VERY balanced while on the other hand the HD700s come off as a more 'fun' headphone. Both are very good but I would give the HD700s a slightly better edge especially with the Bifrost uber upgrade I just installed today.