So I have a HD 555 and I removed the rubber thingy inside which supposedly turns it into a HD 598 offcourse what I noticed was garbage bass now that it has been removed there is no bass. I wonder what kind of upgrade in quality am I going to experience with a HD 650? I use a Xonar DG sound card the Amp does 150 ohms headphones on "exciter mode" I wanted the wood cup fostex but at $525 it just seems way too expensive. And I am NOT interested in mass drop my purchase MUST be on Amazon and also direct from Amazon llc for reasons I am not willing to discuss here. I hate how little to no sub bass the modded HD 555 are currently, and I also LOVE open back headphones and I love the sennheiser sound signature it's one of a kind I love the dark laid back tone of my HD 555 I never found ANYTHING that replaces this beauty of a sound I get from these and I tried many headphones. My music are lots of movie sound track, Interstellar hans Zimmer and well other stuff like Lana Del Rey because her music has this really laid back dark cold vibe to it. I have heard the HiFi man 400i is a better headphone than the Hd 650 but I dunno. I liked the look of the Fostex planar magnetic headphones and the price is nice at $375 but Zeos Reviews guy said they are terrible and to stay far away from them.