Philips shp 9500 is great but costs double, upwards of 10k.Has the 599 SE been discontinued?
Are there any other good open back over ear headphones in the same price range?
As another member suggested hifiman he400se are also very good. They may require amp but I am not sure.
There had been postings of both hd598 and 400se here on techenclave for decent price so if you can be patient you might get a great deal.