It's never a good idea to add a small, cheap mixer between a DJ controller and a BASSBOSS system. It's a low-quality piece of equipment compared to a high-quality controller and your subwoofer and tops, and compromises your sound quality. In short, it does not help and can often cause problems and even driver failures.
Having tested the performance of common small mixers, we can report that they begin to distort below nominal output level and distorts massively when higher output is demanded. Although inputs and outputs may be set to “0”, in tests that mixer couldn’t deliver clean output even well below that level.
Using inputs other than 7 and 8 allows separate control of the left and right levels but it also has the potential for delivering an additional 6dB of signal to the mixer outputs due to what’s called “double-bussing”.
The combination of double-bussing and running the levels on the mixer at “0” is likely to make the situation even worse. Any speaker connected to one of these mixers will be amplifying its distortion, and we have seen that customers who had failures often have had these mixers in their systems. Removing the mixers has been the solution in several cases.
A subwoofer with a powerful amplifier that’s intended to reproduce very low frequencies is more susceptible to damage from this type of signal distortion because it has the power to amplify the distortions and because the frequencies at which the distortions occur are not filtered out. Those frequencies are not filtered out so that when they are in the music, the notes get played. Keep it short and sweet - Using an inexpensive mixer in your signal chain is never recommended.