I have more then 15 hours of listenning throught my D7 and I have another obserbation to share. My Klipsh Image One are already strong on Bass and the D7 seems to boost the bass a little bit so you loose definition in the lower mids wich affect some male voices. I guess that the D7 would perform better with a "monitoring" type of headphone like the Audio Technica M-50.
I still love my D7 and I was planning to get the M-50 anyway ... I just thought that it could be helpfull to share this observation.