When you use speakers, its all about what envirnoment you are using and your sound card and how it is set up. The first part, about envirnoment: When you have the headphones right next to you, you can hear everything since they are so close. But with speakers the speakers have to go against your PC's fans, and any other sound that is present. Sometimes the sound card have a program built in that goes to act against these background noises and have pre-set equalizer settings to hear the best: So when you have a a rap song you would set it to either hip-hop or a rap setting and it would increase bass alot and also let voices come through. But sometimes your speakers, not saying yours are, but they can barely produce computer sounds. I'm assuming you have a 2-speaker set up through an internal sound card? But yea, got any questions, ask away, though I'm not the best audio geek here, hopefully some one with some more expertise will help, but that is my answer.
-Ibrahim

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