Have A new Sub

The amplifier you have was a bit over-kill for the L5.  They're rated at 450 watts RMS.  That 600.1 is rated at 600 watts RMS at 13.8 volts.  Since cars typically put out 14.4 volts,  it's actually putting out closer to 700 watts RMS.  If you were reallllllly cranking those woofers with the gain set improperly, and the bass boost on,  it is possible to fry them.  Another way to fry them is not getting enough power to the amp.  If your electrical system cant provide a good amount of current to the amplifier, the amplifier will start putting out DC power, which will definately destroy a speaker in time.Just remember, the gain isn't a volume control.  It is merely a method of matching the signal put out by head unit.  While breaking in the woofers,  the bass boost should be off completely (and don't use any bass remote), and head unit bass options should be off.  The gain shouldn't be set high in any case.  Also, depending on what Kicker reccommends, break in should last about 30 hours.In any case, something is definately wrong if your subs are smoking.  If you don't feel comfortable doing the installation on your own, or you don't know everyting you're doing, take it to a professional (and that excludes Best Buy or Circuit CIty).  For  a few bucks, a pro will set it up for you properly, so that you don't destroy your car or stereo.