While you can prefer the sound of one thing over another, but that doesn't make it totally subjective. Things can be wrong sound quality wise as far as accuracy and tonality. Just because you personally like it, doesn't mean it is actually being reproduced the way it was originally intended (which is true sound quality; the reproduction should sound just like it was intended when recorded, no more no less).
Anyways saintluey, if you've ever heard a good setup (and likewise a bad setup), you'd know the differences. It's less obvious on music like rap than it is with rock/classical/etc...real music. Take a double-peddle kick-drum being played at a fast tempo. On a sub setup with good sound quality, each "hit" should sound very tight and independent of the next "hit", and it should sound like you were standing right next to the actual drum and not just a "thud". If you listened to that same double-peddle kick-drum on a sub setup with poor sound quality, each "hit" would be hard to differentiate from the next "hit".....it'd sound more like a constant flow rather than independent hits, and they'd sound more like thuds rather than an actual sound.
