Do yourself a favor and try a quality basshead headphone. Using the XB500 as the reference for bass will do your ears a disservice. Listen to a Denon D2000, Ultrasone Pro900 or M-Audio Q40 for example - your perspective WILL change.
On the open side, the Phillips Fidelio X1 is a Bassy can. Loved it.
Many of us thought the XB500 was the Schiit before we had real phones to compare it to.
I totally understand that. I still listen to budget headphones, but if I decide to upgrade (that won't / can't happen anytime soon), the Fidelio would actually be something I'd really like to try. I must admit that I still prefer warm sound.
Oh, and now - 2 weeks later - I still own the XB's. I guess I shouldn't have considered them sold before I receive payment.... I actually used them to watch youtube last night. They are pretty light & comfortable, but they simply don't work for music (for me).