Digital converters need a stable clock source, if there is no clock source to guide the converters, they may actually just generate noise until it can find a solid clock source. When switching audio frequencies on the Studio 192, and you don't switch the external device first, may cause a preamp to generate digital distortion as many devices have no muting circuit of their own.
As you cycle through the frequencies, returning to the correct frequency there can be constant corrupt audio until Studio 192 clock source is switched to another and back. The Studio 192 will mute this unknown clock source as quickly as possible, however some unsynced audio may be audible for a brief moment.
It's always a good idea to turn down your monitors before attempting switching sample rates between external and host interfaces. This is not unique to the Studio 192 and should be considered to be a best practice in your studio.