You asked, "If I purchase a SACD player, do I still need the Geer Fab Box in order to hear the DSD layer of the SACD."
The answer to that is no. The SACD player will play the SACD layer from its analog outputs. But, unless something has changed magically over the years, you will need to have an SACD player (or SACD transport) in any event because you need the laser in it that reads the SACD layer of the disc. It wasn't clear in your post if you were planning on that.

