A large proportion of loudspeakers are termed ‘bookshelf’ speakers, yet despite this term, they will perform better on a purposely built speaker stand than on a bookshelf.
The quality of the speaker-stand will have a very marked impact on the performance of your speakers. Firstly they must be very rigid. Speakers work by moving air, and as they push air forward there is a tendency for the speaker to rock backwards, reducing the impact of the music. The more stable the stand, the tighter and more controlled you music will sound.
Nor should the stands store energy and transfer it back into the speakers. Good stands can be expensive, but it is money well spent.