No comparison. The bass on the hd650 is basically just "there". Kinda just filling up space. The bass on the d5000 makes itself known. Of course, it depends on what you are listening to. I put in the planet of the apes (2001) soundtrack and listened to the last song. I was blown away! I have never, ever, ever heard such bass. It was awesome. It was, well, it's cliche, but it was thunderous. It just reverberated forever. But it was also not overpowering the other frequencies, not crowding them out at all. I am a basshead so I really appreciate that. Overall the sound is just more aggressive, with more detail, IMO. But I am getting ahead of myself, I have only listened to them for maybe 5 or 6 hours.