ok guys I see that some are waiting for an opinion on the cable upgrade. first off Iam going to say that I won't get into the debate over whether or not I think that the upgrade makes the 590 better than the 600, its just not worth it. My opinion is that the 590 and the 600 are both great phones, just for different people, my advice to anyone who is thinking of purchasing either should audition them first, with a disc that they are very familiar with. Iam far from an "audiophile" and I try not to use the lingo just because I really do not understand what it all means, without having someone who is an audiophile to explain just what I'm hearing and what is the proper terminlogy to express this. so here goes- short and sweet: my review is based on the hd590 with stephan audioart cable listening to radiohead "ok computer" with my headroom little with outlaw interconnects and a sony dvp s550d cd/dvd player. my first impression was the great bass presention, much tighter than with the stock cable. also the separation of the instruments seemed more noticeable, seemed more like being in the recording studio with the band. Also I noticed a crispness in the higher treble sections where synthesizers are used. It seemed like some of the muddiness that I (my opinion only) noticed was no longer present, overall a much crisper sound in general. And lastly the headphones seem to be overall more accurate than with the stock cable, more punchy if that makes sense. I would not make recommendations on what other people should do with their money but as someone who has had the 590s for a long time I would say that I am very happy with the money spent on this cable. sorry that this review might not be up to par with some of the more experienced people on this forum but I gave it a shot, if there is something that you guys want explained in more detail feel free to post the question and I will try to answer it if I can. Hope this helps you guys......