The RS-1 has a larger driver and housing than the RS-2, however, the RS-2 is probably closer to the traditional Grado sound, IMO. The RS-1 isn't unpopular, but there are more people that say they didn't prefer the RS-1 sound than say that about the RS-2. I've only heard the RS-1 once, and I wasn't able to compare it to any other Grado at the time.Hi ..could you say what is the difference between the reference series? I want to buy my first grado.
I did own the RS-2E for about a year and loved it, but needed to sell it during a down time, and am now back with the SR-325i, an older model.
The RS-2 sound is the typical Grado "lively", "dynamic" sound, but also very refined sounding. All Grado's make rock, esp. guitar rock sound it's best. But the SR-325 is also a great sounding phone, and really only just a hair behind the RS-2.
One other thing, the newer "X" series Grado's (RS-1X / 2X) are a bit "darker" sounding than the older "E" versions of the same phones. Many years ago, Grado's were accused of being "too bright" (esp. compared to boring Sennheiser phones!), so Grado has slowly been toning down the treble output, which IMO, is a shame. But it depends on what you are looking for.
Good luck searching!