"How again can you tell that 48khz is being fed to the DAC's for analog? I have an s300 but I simply can't remember."
You have to open it up and measure it. The S300 uses PCM1791 DACs. Pin 1 on those DACs is the Left/Right clock. That clock cycles once per sample. IOW that clock runs at the sampling rate of the signal going to the DACs. R051 is connected to Pin 1 on the PCM1791. Measure that clock with a frequency counter or a scope and you know the sampling rate of the data going to the DAC.
The attached show this on the S300 when playing back the Dave Matthews BluRay with the 96kHz track selected. The S300 DACs are being fed at 48kHz, the core data rate just like the 95FD.