When you EQ to try and find a *better* sound, do you find yourself increasing the bass frequencies to get closer to what you like? My guess is that you've trained your ears to a particular sound and the 225s aren't filling that need.
I had a quasi-similar experience with my first "high-end" headphone... the SR125. Obviously not a real high-end can, but one that is supposed to preform much better than say the Bose Triport OE (cans that I had demoed at Target several times). I was completely unimpressed at first. I told myself that I liked them, and there were lot's of things that I DID like about them, but one of the first tracks I listened to was "Dead Bodies Everywhere" by Korn because I thought I'd hear an earth-shattering amount of bass... it wasn't there.
But then I actually listened to them for a while and realized something.. I could actually HEAR the bass! It wasn't in your face, but it was clean, pristine. There was no bloat, the notes where distinct, I could see the bass player actually playing an instrument as opposed to a sheer wall of sound that had no definition. Now, the 125 is a bass light phone, and can be tiring with it's top end harshness, but I found that I really appreciated them after a few months listening, and no speakers - including those in my car that can rattle the mirrors with their bass - could replicate the joy I got from those headphones... obviously I don't have a quality speaker rig to listen too... much to expensive for me, but the point remains. I realized that bass needs to be in balance with the rest of the sound, and also needs to be clean and controlled in order for the music to really sound good!
Now, you might not ever feel that way, and prefer a punchier bass that (IMO) drowns out a bit of the rest of the sound spectrum, and that's perfectly OKAY, but you should take the time to really think about what you want out of a phone. If the QC2s give you that, then by all means stick with them! If not, then try some other cans (already mentioned above) and find what you are really looking for in a system.
BTW, I second the notion of trying another source. Most computer sources are blah, particularly if the sound card is an integrated solution to the motherboard. An amp will help, but there won't be dramatic improvement with a neutral amp. Some amps out there are far from neutral, and might do the trick in warming up your 225s to your taste... but I'd avoid that unless you are willing to spend a lot of money and time in the FS forums and comparing amps. Finding a headphone with your sound sig and then going with a neutral amp that improves that sig is probably the cheaper way to go.
As a last bet, and it will certainly be unpopular to most people on this forum, go to bestbuy and demo Beats by Dr. Dre. Not a good can, for me, especially at the price, but certainly they have the bass punch that you might like, plus some of the isolation that the Bose offers. I don't think the Beats offers as good isolation, but I think they have better sound quality. You might find some used for cheaper, or if you really like the sound, just buy them! They'll make you happy, and really that's what this should be about.
