I really think that the style and price point of these cans makes re-cabling either an amusing exercises or a really dedicated head-fier. I personally think they sounds very fine with the stock cable, and I couldn't imagine ripping them apart and spending more money on cables to make them sound anywhere from slightly better to a bit better. I know some will disagree with me, but the question to ask about re-cabling the 598s is: "Do I REALLY want to do this?" If yes, then please post some pics.
Edit: In essence. You do not need to re-cable to make them sound good. They are just that from the get go.
Most of what I have read concerning these hp's has led me to believe they are, as you say, good from the word go. I wouldn't be interested in buying something I would have to perform surgery on to achieve a sound I believed existed naturally. I'm replacing a pair of sr60's that lost it's left channel after a couple of years use. Thank you for your input.