H, since you didn't mention it, I'll again point out that unless your room is very large you may find that setting the trim control to half or even full may give a smoother overall response.
Your comment that the sub is "trying to play all the audio" isn't entirely clear, but may indicate that the level is simply set too high. The sub shouldn't be heard as a separate source; the impression should be that it isn't working but that the speakers are putting out more bass. The level can either be set by the auto calibration or manually with the aid of the SPL meter, although considering that the manual level setting adds a human error factor, it's unlikely to be more accurate(or even as accurate)than the job the receiver will do.
