I owned the buttoned RS-2 and the buttonless non i RS-1 at the same time (along with the 325i and the sr80i)
I listened to them through a macbook pro > lossless > Apogee Duet
I found the RS-2 and RS-1 to be very different headphones. Though both are very resolving and detailed.
I found the sound signature closer between the RS1 and the 325i vs. the RS-2.
I was listening to the RS-1 and the 325i the majority of the time, so I let the RS-2 go.
If you look at the headroom frequency response graphs for the RS-2 and RS-1 (yeah I know
) the 4-5k hz boost of the RS-1 and the 5-6k hz boost of the RS-2 illustrate what I found to be the differences when I compared the two phones.
I remember that I thought the vocals on the RS-2 were more prominent and emphasized, female vocals were really sweet, perhaps because of a little less bass and the slight gain of the RS-2 at 3-4k.
I thought there was more of a "fullness" and coherency to the RS-1 ( I remember I thought the RS-1 was "smoother" ) when compared directly to the RS-2, but with the RS-1 occasionally having too much of a mid-bass hump depending on the music.
I can see why some people would prefer the RS-2 to the RS-1. The treble was less fatiguing, the bass was tighter and the RS-2 had a SLAM! (the attack of the drums and percussion) that is not as prominent on the RS-1.
Overall I prefer RS-1 to the RS-2 and 325i, but the 325i did something to guitars that I miss when listening to the same song with the RS-1.
In the end it was something missing in the "fullness" of the guitars (maybe decay?) that really bothered me when l listened to the RS-2's. I could not get over it.
Sometimes I really miss the RS-2, but not enough to buy another one ( yet).