No way, that has got to be your amp.
The rest of the comparison was spot on though for your pair of K340's. I'm so jealous of your RS-1's. I don't think that comparison is very good... but you've been a Grado fanboy longer than I have, so who knows. Well, this was on my rig and Massive Attack has good recording quality, so there wasn't anything too terrible going on. The flats just made the bass go like woah.