There is a limit to the sound you can get out of a wooden box so it is not possible to improve the sound just by using different drivers.Well, no, there isn't. Because its not the box that makes the sound. Its the drivers AND the box. So improving drivers can indeed improve the sound even if the box stays the same.
Also not only the box but the materials inside the box affect and are able to improve sound quality. Not to mention the shape of the box, its size, and construction. If the box is ported, sealed, transmission line or folded horn that will also affect the sound quality. So its possible to use the same drivers and have greater or lesser sound quality from the same wooden materials simply by changing the way they are used.
You seem to be awfully concerned with speakers kenjit. I do hope you are getting this. Its really useful information if you want to understand them better.