the 570's are at fry electronics (outpost.com) for about $40.
search for 570 & 590 threads.
personally i don't like the senn egg shapes as they put the transducer about 1/2" above the ear canal. perhaps it's for this reason why many people preferr the 580's over the 590's. putting the transducer .5" above the ear canal will likely decrase highs and mids - giving you a false sense of bass and mid bass.
the hd600 has 600 ohm imoedence, the hd580 has 300 ohm impedence and the hd590 has 90 ohm impedence. so pairing a hd590 will lower impedence sources will then tend to make the 590's sound better (with flabby or muddy bass) (greater volume) while mating the hd580's will give it a false sense of bass and recessed mids.
so consider your source - this is why many people say that if you get the hd580 or hd600 you need an headphone amp. personally i don't like the cheap wiring on the senn's and can't see paying $190 for wiring on a $200 set of headphones. it's much better to just buy a $400 set of headphones and be done with it.
to summ up - the 570's are crap. don't waste your money. you'll have to get the opinions of people who own the 590's and make a better judgement.
i suggest you open your phone book and call all the audio dealers within a 100 mile radius of you and listen to as many cans as you can. don't forget to take 3 cd's that you're intimately familiar with. and then throw two others that are of different gendre's (like classical, jazz, bigband, folk, bluegrass, etc) to get an idea of what they can do across a wide spectrum of music. me, i like vocals, viloins and horns to listen to cans (i preferr clear mids with tight bass and non shrilly highs).
