Got a pair of the HE-400 for the second time, this time with the Focus-A Pads. I remember the HE-400 having great bass, but I'm honestly surprised that the HD650 keeps up with them very well. Perhaps it's because I'm unknowingly volume matching using treble, which would push the HE-400 bass down and the HD650 bas up, relatively speaking. Either way, I thought having the HE-400 again would be a nice option for when I wanted a bit more excitement listening to electronic music, but I'm not so sure it's necessary.
I'm also surprised in a different way. With the Focus Pads and an HD600 headband cushion on the HE-400, it's actually feeling a bit more comfortable than the HD650, despite the weight difference. They fit around the ear better, are a bit softer, and with less clamping force. So, instead of putting on the HE-400 for livelier bass, I may put them on for more comfort, which seems completely backwards.