My friend just purchased a H/K 225 receiver along with Paradigm Atom speakers for front and surrounds and the cc170 center channel. The sub is the 10" paradigm 100 watt sub (not sure on the model # ) He has a Samsung dvd player which is brand new as well. While watching Gladiator on dvd he said he heard some popping and crackle sounds comming from the rear surrounds. I have not yet looked at how he set everything up so i can't tell you anything other that that. What could be causing that popping sound? I am sure the speakers are set up correctly. Could it be a surge protector problem? I am going to look at the set up tomorrow after work. What should I be looking for? What may be causing this problem? Please respond quickly as he only has a week to return the unit and time is a running out. I put this in the receiver section because I figured it is probably the receiver and not the speakers. Sorry if I should have placed this somewhere else. Thank you in advance.