Heya,
Maybe think about why you want the PRO900 to begin with? I had them for bass-centric music specifically, because they were simply not great for much else (they were awful with vocals, acoustic, indie, folk, classical, etc). They do produce a nice bassy thump. But even then, it's a lot of mid-bass that over powers the sub-bass even. You can get them used, by the way, here in the for sale forums for like $300~350. Take a look. However, if you're just looking for a nice bassy headphone, I'd suggest some alternatives. I found the Panasonic HTF600 to be nearly the same in terms of bass in perceived bass. The Sony XB500 is also a contender there. The PRO900 doesn't slam that much harder. Certainly not worth $500 more for the miniscule difference there is in that department. Other things you could consider would be a Denon 2000 or 5000. They both have a more neutral signature compared to the PRO900. The D5000 however has excellent sub bass, good mid-bass, and still has great mids & treble and wood back (can be had used for around $350~400 often). I actually went from PRO900 to D2000 and much preferred the overall tone in all music, even in EDM, because I'm more of a sub-bass head. I don't want a massive mid-bass hump that drowns out the mids. I liked big sub-bass slams which gave you that bass feel and boom, while you still have nice clear mids & treble. So naturally, I instantly went to the D5000 right after that and I've stuck with it. I look back on the PRO900 and the only thing I really liked about it at this point was how it looked. Beyond that, I much prefer the D5000. So hey, food for thought, since you're willing to drop hundreds on a headphone.
Very best,
