So I bought a pair of C5's at the beginning of my search, and loved the sound but they were uncomfortable and difficult to get situated right. A short time after returning them I tried the P7's and fell in love. I've been using the P7's ever since and love them, but have been looking for a complimentary portable. I have tried all of the P7's top competitors and none had the sound signature I was after. So for Father's Day I had the wife get me the C5's. I was both delighted and again disappointed. I loved the sound, but you had to get them in perfectly. The fit and comfort was just too delicate to find the sweet spot. As the yew re a gift from the wife at this point, I decided to go them more time and energy to see what I could do. In the end I decided to order some TX-400 Comply tips. Working in manufacturing plants sometimes, I know that you need to compress these kinds of tips and let them expand in your ear. So I rolled the large tip in my fingers and stuck it in my ear. When looking at it before sticking it in my ear, I noticed the driver was mostly covered by the tip and the hole had shrunk considerably. The sound reflected this; muffled highs and just not a good sound at all. So I pulled them out and this time used three fingers to push down on the tip toward the driver, then rolled the tip around the driver. Now the face was completely exposed and I stuffed it back in my ear. Ahhh! Jackpot! Just what I've been looking for! People say the P7 as bass heavy and bloated, but I have never felt that way. To me it is very balanced and just the perfect sound signature for my ears. Now that I have "dialed in" the C5, it may be even better. Slightly brighter highs, slightly more exaggerated bass (I'm not in the extreme bass club, but I like emphasized bass.) These things sound incredible now.
My use case is actually opposite to what one might expect. I carry my P7's back and forth to work, but they stay in my work bag. The C5's will stay in my nightstand to use when the wife is sleeping. I might actually prefer the sound of the C5 now, but they are more difficult to take in and out. At work I get many interruptions, and it's just far easier to slide the P7's on and off. I am excited to spend more time with my C5/TX-400 combo!