Lets recap on an important part of the OP. First there may be a component that inverts the phase (for this discussion, lets just use this term and not polarity) of the music. That is something that should be stated in the manufacturers spec sheet. That is NOT what is being discussed here. Secondly, it is possible to connect one or both speakers out of phase, either with the amplifier or each other, but not both. Think in terms of a car battery. Red to positive, black to negative. Same thinking goes with your amp and speakers, but in 'stereo'. So then, if just one of the speakers is wired out of phase in relationship with the other speaker (think red to black, and black to red at the connections on one end OR the other), this is what the OP was describing. It results in a loss of bass, and a wider than 'right' soundstage, where there are poor positions recognized for the musicians.