Hi grnspyderrs,
Different manufacturers have different philosophies regarding clocking. Unfortunately, of all the server manufacturers out there to the best of my knowledge only Aurender offers options that are philosophically aligned with dCS (see my post in this other thread for more detail) and can be connected according to dCS’s preferred clocking schemes.
The bottom line is that with the K50, your only option is to use the embedded word clock in the AES3 signal, to do this set the Sync Mode in your Rossini DAC to A for Audio. Your Rossini Master Clock is redundant in this configuration.
Mark appears to be mixing things up a bit, I don’t think he fully understands the dCS clocking architecture. No dCS DACs have a Reference Clock input (a Reference Clock is a clock that runs at 10 MHz, as opposed to a Word Clock which runs at an integer multiple of the sampling rate, either 44.1 kHz or 48 kHz). In the dCS product range only the Vivaldi Master Clock has such an input and it can be configured to accept either a square wave (‘TTL’) or a sine wave (‘AC’). Those options are not relevant for the Word Clock inputs on the DACs.
As an aside, I find it strange that a music server, which is a digital source, should have a clock output. I thought most companies accepted that the preferred clocking schemes are based on either an external master clock or having the DAC provide the master clock, both of which require a word clock input on the source. That said, this is all hypothetical to a degree. If feeding your Rossini from the K50 sounds better than the internal streamer then who cares about philosophical differences over clocking?