Hopefully there's someone out there that's gone through a similar journey.

Budget - $400USD Source - What are you plugging these into?Components: Furutech ADL GT40, Bravo Ocean, AQ DF Black, Sansui AU919, Macbook SOURCE: Vinyl, lossless digital
Requirements for Isolation - Open, home use only. Unless there is a comparable closed equivalent...
Will you be using these Headphones in Public? No, home. Sound bleed does not matter
Preferred Type of Headphone - Full sized
Preferred tonal balance - I'm not a basshead but do like bass, particularly when it's tight and punchy. I'll say I really liked the HD600s but wanted just a little more forwardness. I thought the 650s would solve this but I was wrong.
Past headphones - HD600 (alot what I was looking for thought the 650 would be the fruition of it), 650 (the bass I wanted was more muddy than punchy), AKG 701 (blah but probably weren't amped enough, didnt really have the juice when I tried them), HD598 (no detail, like the 650s IMO, though theyre a pleasure to listen to and forgiving, ultimately I think theyre veiled)
Preferred Music - Jazz, alt and classic rock, folk, soul, r&b
What would you like to improve on from your set-up - I want HD600s with the bass a bit more forward. Also not an absolute requirement but I dont have a 'desktop setup' and use a lot of vintage equipment so will probably get more use out of any easier to drive headphone. I'm leaning toward the X2s but may be way off, maybe something else is out there. "Maybe she's not wearing panties. Or maybe shes wearing something I havent even heard of"