I have a Yammy receiver. The crossover is 90Hz built in to the receiver, which means if a subwoofer is connected and any speakers are set to small, anything below the 90Hz goes to the sub. I have my subs crossover dial on the back of the sub at 105Hz. I have all speakers set to SMALL, and I have the option of setting bass/sw to NONE, SUB, or BOTH. I currently have it set to BOTH. Now my question is, is this really the correct way to do things? What frequency ranges actually travel to the mains if I have the setting on BOTH? My understanding is if I have the mains set to small, then nothing below the receivers built-in crossover of 90Hz will be sent. But now that I have bass set to BOTH, what is actually happening here? I'm just curious and appreciate any advice in this matter.