Your son is correct that it is a powered subwoofer. The black/red/blue wires are pretty standard for the power for an amp. Red - power; Black - ground; and blue - turn-on trigger. More than likely, the two white wires were for a high level (speaker level) input, but since you had RCA cables, you were getting the signal that way instead of via speaker wires. It still would be wired incorrectly if the amp was on when the stereo wasn't though. The amp should turn on/off with the stereo. Bottom line, it shouldn't create any problems sitting in the closet in the house.