Hey OP, sorry for digging up this 2-month-old thread, but I have a few questions about the HD650 and the HE400. Originally, I wanted to try out the HE400 since many people compliment on its great bass. I usually listen to sad pop songs with high vocal and occasionally deep bass, so the bass really stands out amidst the high parts. Therefore, deep, impactful bass makes the songs sound so much better! I went to an electronic store before to try out as many headphones as I could before deciding which one to buy, and the factor that made me say "yes, this is the one" was the quality of the bass. As you can see, I consider the bass an important element in my music, and the HE400, naturally, would be a good choice. However, after reading your comparison between the two, I learn that the HD400 is quite "energetic", "dynamic", and "unnatural" on the mid and high range. This could be a problem, since I wouldn't want the vocal, which apparently is the main part of the song, to be rough and unrefined. Also, I wouldn't want these sad songs to be too "fast" and "engaging", as I prefer a warm, rich, and processed sound. Do you think the HE400 would be a good fit for sad pop songs? Do you prefer listening to the HD650 for that? Or is there not a big difference between the two?