Yeah, we don't talk about headphones any more, just drinking.
Kidding; welcome back; etc.
If memory serves, recabling is necessary, but nothing stands out. The biggest difference is going from stock to pretty much any decent upgrade cable. I prefer the Cardas, but that's MHO.
Sure wouldn't hurt to get a balanced one to go with your amp. 4 pin XLR? Might see if one of the DIY guys would solder something together for you.
And yes, if you're going for comfort, you can't do much better than the Sennheiser HD600/HD580/HD650. Excellent choice.