Hi all....new to the forum and have a couple questions. I've just picked up a pair of well taken care of SDA 2s. I believe they are SDA 2 b. Two drivers one tweeter. When i play them they seem to get stressed and one side fades. This happens with or without the interconnect cable. Any thoughts on what the problem could be? I am powering them with an Onkyo 7.1 reciver.