My communications with other audiophiles and my experience with integrateds says that putting a sub or any electronics in the signal between the pre out and main ins will have an affect (likely negative) on the sonics of your system. There are many integrateds that have seperate pre outs or in some cases line outs that can easily accomodate a subwoofer(s) without in any way affecting the signal fed from your amp section to the speakers. I recently tried the Dussun V8i intergrated, which is in my opinion one of the best bargains in audio and a very fine integrated. However it has pre outs and main ins too, but no seperate pre outs. So, with this integrated your only choice is to connect a subwoofer via the pre outs and main ins. Since I had subs I wanted to hook up, that became a deal-breaker for me and I returned the Dussun. For me, seperate pre outs are the way to go to connects subs.