rega planet 2000 is one of the best matches with rs-1, but i'm guessing you're looking for something more 'hi-fi'. i went from cary cd-303/200 to krell kav-300cd. the krell and rs1 with gilmore played together real nice. cary is better suited for senn hd600. i will be selling the krell later if you are interested, i'm making a switch to computer based transport so i need a dac.
linn ikemi is another good one. i'd like to audition a naim source one of these days...
i got audio technica ath-cm7ti a week ago for use with rio karma and 4gen ipod, these are pretty nice earbuds. the sound is midrangy, voices sound so clear. they're not speedy like the etys but it's really smooth and plenty of detail. ordered them from j&r, give them a try...