To tell you the honest truth, I didn't even bother to directly compare them. I don't care enough to go through the trouble. The 6.3s have a lot more treble, but the rest of their sound was very familiar to me, because I have owned the RC-70s for a long time now. For low listening levels, I think the 6.3s are really great, but I could never use them for loud, long listening periods. The finish on the 6.3s is incredible compared to the black ash and cherry finish of the RC-70s.