I am on El Capitan on an early 2011 MacBook Pro running Adobe Creative Suite CS5.5 Production Premium. Sounds I play through most applications (QuickTime, Finder, iTunes, etc.) sound very different from the same sounds played through Adobe Audition or Premiere Pro. It sounds as though there is some sort of equalizer or loudness compression that is being applied at a system level, but which is being bypassed with the Adobe apps due to the way they work with audio hardware.
I installed Boom and Soundflower years ago attempting to get a system-wide EQ, but have long since uninstalled both of them - and I just re-ran uninstall scripts from both developers to ensure that all the relevant kext files have been removed.