ok so, i have been looking into some performance headphones and i was wondering what would the best ones be as far as build quality and sound, i have been looking at the beyerdynamic 880's and 990's, the sennheiser 595's 600's and 650's and some of the grado labs headphones but i don't know much about them. i am looking for both home and portable use and i can see it as a shame for some of these headphones to be used on say an ipod, but i do have an amp for home use. what would be the best all round unit i have been steering toward the 990's or the hd595 but i would like some imput thanks