The differences between the SA and the SAT relates to the pickup and electronics. These are:
SA Pickups – LR Baggs Element undersaddle acoustic pickup plus a lipstick style single coil.
SAT Pickups – LR Baggs Element undersaddle acoustic pickup plus a Kent Armstrong P90 style humbucker.
The SA features a preamplifier fitted to the top bout of the guitar with controls for bass, mid, treble, volume and a blend control. The outputs of the pickups are mixed and blended together after which the volume and tone of the blended sound is processed and sent to a single mono jack output.
The SAT has rotary volume and active tone control for each pickup and the outputs are sent to a stereo output jack so that each pickup can be routed to its own amplifier. If a standard mono jack cable is used the outputs of the two pickups are mixed and the mix (or blending) can be controlled with the volume controls of the two pickups.