When I use dolby pro-logic, or pro-logic II music, my rear speakers seem to cut in and out depending on the frequency (high - in, low = out). Someone told me that this is because it is a analog source, and I should use pro-logic IIex (which I dont have). Is there a simple explanation for this? Oh, on a side note, in speaker configuration, I can set my rears for high or low, and when there on low it doesnt seem to be that noticble, or not at all. Thanks