Thanks for all the responses everyone!
I now own a pair of HifiMan HE-400's, but I'm still searching for the perfect bass-heavy cans. I'm researching everything that you all are suggesting, and have managed to listen to a few of them in person. More suggestions are always welcome!
Good choice! Wouldn't call them bass head cans, but I will call them the best headphones under $699 tho. What do you think so far? What are you using to power them??