Maret, the "crossover"(actually it's just a low-pass filter on the sub, not a full crossover)affects either the line level or high level inputs unless it's set to "bypass". As mentioned, I didn't find any benefit in adding it to the filtering on the sub that the receiver was already doing. Note that the amended direction in the manual now suggests setting it at or above the highest receiver crossover set, so the effect would be to increase the steepness of the rolloff of the sub above that same frequency, compared to what would result from the receiver filter alone.
