“This upgrade entirely bypasses the AKM audio circuit and the associated high jitter clocks. The mod was designed to integrate the Sonos into your high end audio system through an external DAC. This new custom board is installed in the Sonos and directly converts the I²S into up-sampled SPDIF. This new ultra clean low jitter signal is now available through the replaced coax digital output. The SPDIF output sample rate is fixed to the most popular 96kHz sample rate. “ (wyred4soumd.com)
The modifications includes a much better coax output port.