A hairline scratch on the hinge is really nothing, but if that is going to bug you then send it back. You still have the 1 year warranty on the first one, so if the speaker issue pops back up again you can have it dealt with at that time.
Personally.....I would keep the second one. A scratch on the hinge is not a huge deal for me and the fact that the speakers on the original had issues once leads me to wonder if it isn't something lurking. The potential of having to deal with that down the road is enough to make me send it back.
Moral of the story being that there really is no wrong answer here. You'll be fine either way. Just figure out which factor is most important to you.
Personally.....I would keep the second one. A scratch on the hinge is not a huge deal for me and the fact that the speakers on the original had issues once leads me to wonder if it isn't something lurking. The potential of having to deal with that down the road is enough to make me send it back.
Moral of the story being that there really is no wrong answer here. You'll be fine either way. Just figure out which factor is most important to you.