Your amplifier will not work properly because it has no negative feedback from its output to inverting input pin 2 like EVERY circuit shown in its datasheet. Also your circuit is missing an input coupling capacitor.
If you use a differential amplifier to hear a stereo sound then there will be an output ONLY when the two channels sound different. Bass sounds and vocals are usually mono (the same on both channels) then they will cancel and produce no output.
Maybe instead you want to add (mix) the channels to produce mono?