If your speakers are connected improperly (ie polarities are reversed) they will be out of phase and the sound that eminates will be diffuse rather than focused (discrete sound stage of a normal stereo setup). You will not hurt anything, turn off your amplifier and simply reverse the polarity of the one channel you suspect is out of phase and the problem will be corrected. Next, indetermining if you have a bad channel, try reversing the right and left channels of one of your input sources. If the music plays in the previously "dead" speaker, and not in the previously good one, then something is wrong in the amplifier or one of it's connections. Hope this advise helps. Happy listening.