Well, I tuned the ZO2 to "correct" this problem. The so-called "personal subwoofer" does ironically, put that "Kelton subwoofer" to use without destroying the brilliant vocals. The sound is just complete. The crazy thing is that the ZO2 on barely a few steps in it's "green" setting, is still pushing the bass pretty hard. Any higher and it distorts the sound, as the C5 does.
It has this illusion of sounding "less clear" now that the bass is more prominent, but it's just that: the added bass can be distracting from the vocals if you enjoy beats.
Edited by BlinkST - 6/26/13 at 1:35pm