Hi Brett,
first of all - ensure to close down the Standalone and delete your Synchron Player Standalone preferences file:
%APPDATA%\VSL\Vienna Synchron Player Standalone.ini
This will ensure that we're starting from a fresh situation.
Then, select the RME driver only, choosing your preferred samplerate and latency. Please note that using a samplerate other than 44.1kHz will just cause a higher CPU usage and worse sound, since everything has to run through a samplerate converter.
Switching samplerates with the RME driver should be possible from the preferences window, without any strange artifacts as you have reported.
Regarding ASIO4ALL, I have tested this driver together with RME Fireface UCX, and I cannot make it work at all when switching between samplerates, regardless if I'm doing so in a VSL product or simply just in Cubase or Nuendo. I would not recommend anyone using this driver, if you already have a proper soundcard with a proper ASIO driver.