Apple in ear crackling

Hello all. I just bought the apple in ear and I'm impressed by its clarity, good bass, and instrument separation. But sometime I hear little crackling from it. I'm not sure if it's from the earphone. My source is a 2 years old iPhone 3GS, Coldplay, Pearl Jam and The Beatles all are iTunes purchase. I did try playing again and again the part where the crackling happens. It looks like the crackling is from the source but I'm not sure. IS there another effective way to test if your earphone has crackling problems?

I only have another very cheap earbud so I think can't use it to compare right?

Another question: Could you point me some headphone around 100$ that has the same sound signature like the apple in ear. Which is clarity, realistic, and relaxing.

Thanks for reading.