I am a drummer with an electronic kit and am looking for a PA to use for my drums and the rest of the band. I am considering a Bag End P-S18E-I powered subwoofer. My question relates to the speakers. Is it recommended to use the same brand on top? Will there be time-align problems and if so, how do I correct them? Will any brand give good results? What do you look for when matching a sub to speakers? Thanks.