After listening to the IE7's for a month and a half, I have become quite fond of them. However, it hasn't been a very nice month and a half, since i've tried so many tips to find the perfect tips. First i tried the large stock tips, then moved on to the double flange, the ebay tips, the foam and stock tip mod, everything you can think of. But then I found the perfect tips for myself when I used some sony tips that I completely forgot about... I think its the sony ep-ex10A large stock tips. Worked great for me because it was as comfortable as the large stock tip, but it didnt slip out easily. The sennheiser large stock tip is very "slippery" while the sony epex-10A sort've stick to your ears. perfect for me.
As for the sound quality, the IE7s are amazing. The bass is punchy, the mids are very forward, and the highs are very clear and precise. Though I find the bass to be a bit overpowering for some songs, I do not mind it at all, as long as it doesn't muffle the highs and mids. All in all, I find the IE7s to have a great balance, and I can listen to them for an extended period of time without any fatigue at all.