Sending too much bass to the speakers? Or too much volume on an underpowered system?
How is it wired? Does your eclipse head have 3 pairs of RCA' outputs? I would assume not and that you have the subwoofer wired in with the speakers. Check your manual/head unit for any signs of a crossover control, and think about replacing the head unit for one that does. Or you can find some external amplifiers that have full range "pre-outs". Then you can run an 2 or 4 channel amp for the speakers with a low-pass filter, and a mono amp for the sub(S) running off a high-pass filter.
A cheap option is this:
Wire them in to block bass from overpowering your speakers.