The RS-1s are really, really, really nice phones. Don't let anyone tell you otherwise. We do have our Grado haters on headfi, as well as our share of know-it-alls who will only be too happy to tell you to set fire to the RS-1. Totally bogus. The RS-1 is a very refined headphone with very controlled bass, making it ideal for rock, classical, jazz and acoustic music. What you may have heard was that this is not a headphone for bassheads. That's partly true, as the RS-1 doesn't go out of its way to provide that all-bass signature, where you hear basically nothing but bass 24/7. There are much cheaper phones that will do that, such as Sony's latest sub-$100 bass cranker and Monster's Dr. Dre Beats. But these cans sacrifice clarity and detail to give you throb-throb-throb. The RS-1 won't. It'll give you tight, controlled, bass with outstanding clarity and detail.
Will it throb? Not without a bass amp. I used a solid state amp, the AMB M^3 (price around $500) and, with variable bass boost, got the same throb-throb-throb that other phones provide. All that bass does tend to narrow the soundstage, so even with the RS-1, things can feel a little crowded if you turn the bass boost all the way up. Still, with the RS-1 and a decent amp, you can find the sweet spot where you got all the bass you want - without sacrificing the HF clarity that makes it such a great set of cans.
P.S. I own three M^3s and a B22 - awesome amps - but most of my listening on my RS-1 is unamped.