Quite simply, NO. A "fader" on a car stereo is used to "fade" between the front speaker left/right set and the rear speaker left/right set. Like a "balance" adjusts back and forth between left and right speakers. The Crossfire only has one set of left speakers and one set of right speakers, so there's nothing to "fade" between. As was pointed out, the only way you could "fade" is if you installed another set of left and right speakers somewhere.

If you buy a new head unit that has "non-fading" outputs, that would be ideal, unless you plan to install another set of speakers.