From the PS Audio product page:
The data, which can be up to 192kHz 32 bits, is clocked into a custom Complex Programmable Logic Device that organizes each of the 32-bit frames into the requisite I2S format. That I2S data is then clocked out with extremely low jitter fixed frequency asynchronous clocks and into the PWD through high-speed buffers isolated by a separate power supply.
[Source: @the “Technology” tab]
Also, see here: Forum post RE: DSD