S-X can play louder than S-1, the mid is not as nice as S-1 without the waveguide.
If you plan to get a sub woofer, then go with S-1. You can probably live without a sub with S-X (the bass is a little deeper than S-1 but not much more).
It is a tough decision. S-X is so gorgeous. I will have more photo posted soon. We will not be selling S-1 after the remaining units are sold out. S-X has much bigger commercial appeal.
Jason