First, if the used speakers were driven by adequate amplification they should sound better than new since they are already broken in. Second, if you buy used speakers make sure your amplification is adequate since underpowering speakers will quickly lead to their destruction. In the world of ss amplification there isn't such a thing as too much power. Third, in the real world, your speakers will outlive you if you don't do something stupid.
More speakers get damaged by moving them than playing them. Set them up correctly and leave well enough alone. Learn to power up and down your electronics correctly and keep others away from the controls.
More speakers get damaged by moving them than playing them. Set them up correctly and leave well enough alone. Learn to power up and down your electronics correctly and keep others away from the controls.