I don't think I am an expert, but here's my take.

The QS4's have a bottom firing woofer, so you can't really sit them down on a bookshelf. They do come with wall mounting brackets, I would suggest you mount them to the wall and leave a bit of space for all four driver units to disperse sound.

If this is not possible at all, I would look into either M2i's, M3Ti's, or M22Ti's.