Hi John,
Adding an external Master Clock to your Bartók allows the unit to keep much better “digital time”. For good quality audio, you need the right sample at the right time. The quality of DAC is what makes the right sample, and the quality of the Clock is what makes it at the right time.
While any dCS Clock could be used with the Bartók, bearing in mind the software and hardware improvements we have made over the years you would definitely see the biggest performance increase to the system with a current generation clock, the most popular pairing being the Rossini Clock. In the case of either a Rossini or Vivaldi Clock, you would connect two BNC cables between the clock and the Bartók, to it’s Word Clock Inputs.
The sonic benefits you would hear from adding a Master Clock to your system would be that the clarity of the sound stage (where an instrument or part of the music is left to right but also where it is placed in the mix front to back) is greatly improved, the width of the soundstage becomes much bigger and the ability for the speakers to simply disappear takes a huge jump. It really isn’t a subtle difference, and I would absolutely recommend if you have the option of trying one out for a demo, go for it.