I too have a confession to make, although, it doesn't concern the KSC-35s. I prefer the Grado Sr60s to the Sr225s, both with modded Senn pads. While the 225s certainly have more bass impact I find the Sr60s to sound more transparent and detailed (although they have a peak in the high midrange-lower treble which is annoying). To my ears the sound of the 225s are nice and warm but too thick for me--they are not detailed at all in the lower midrange and bass--just boomy (or thick, as I like to call it).
I've tried them both unamped and amped and my preference still remains. But that's all it is, a preference and I could see how someone could love the Sr225s over all other cans in existence--they're nice, I like them, but they're not for me.
This is why I encourage head-fiers to simply buy all the recommended phones in each price class when they are thinking of upgrading, keep what they want and return or sell the rest. Only then will be sure that you have found the sound that best suits you.
And it's preference, not class that matters. The 225s may be in a different price class than the Sr60s but that doesn't mean that everyone will like them more than the Sr60s (or KSC-35s for that matter). It's all about finding the type of sound that suits you. After you've found that, then think about upgrading but keep your mind open and make sure to try some phones that you think you won't like--the results may be suprising. Don't think I wasn't suprised to find that, to my ears, the D66 Eggos schooled every other closed phone $100 and below (along with most of the open ones to).
P.S. And just to clear up what I said up top--Yes, the 225s are slightly more detailed than the Sr60s throughout most of the midrange and treble but the SR60s are more than slighly more detailed in the lower midrange, bass so I would say, that to me they are the more detailed can--overall and have a more detailed and much more transparent sound although they are, by all accounts, still slightly boomy in the bass, they are still much more refined in the bass than the Sr225s IMO.