i do use full range of rockford stuff, all except the Hu n component. their component are quite good actualy, when we are talking about highest range of product, but the middle range n low range well, it snot that good actually. As for their subs and amplifiers are the best which i would want to regard it. Amplifier have very efficient way in handling powers, amp would not get hot even after u blast it for period of time, and the subs espcially the power or punch series produces deep,powerful bass. excursion limit is hig, and to reach its excursion limit, do need lots of mega power to drive it. Anyway, as for SQL its quite good, as the soudn od SQL bass is actually tuned from the cubical feet of the subwoofer enclosure, as well as the length of the port. The bass of the woofer could be tuned as well, by using the bass boost, and even better for all kind of sound range, if anybody knows a superb product from RF, EPX2. u can virtually tune the sound perfectlly. Anwyay this is my experience. If really for SQL, have to invest in one single woofer with selaed which i also regards as one of the best SQL woofer, JL Audio.