I use the uTrack 24 only in play mode (for backingtracks).
I have exported all my backingtracks at 44.1 kHz 24 bit.
I connect the uTrack 24 to a digital mixer (soundcraft expression 1 that works at a sample rate of 48 kHz) with D-Sub-25 to XRL cables.
I set the internal clock of the uTrack to 44.1 kHz.
Do I have to set the internal clock of the uTrack 24 at the same sample rate of the mixer to work properly?
Do I have to convert all my backing tracks to 48 kHz?
Do I have to connect the mixer and the uTrack with an internal/slave worldclock configuration?
The uTrack24 does not change the sample rate of the song.
So if your system running at 48kHz, you need to have the audio files on the same sample rate. You can do that easily by set 48kHz in the uTool during the song creation or you can also edit your songs.
But if you are using analog outputs on the uTrack24 the two device not necessarily has to be synced together with wordclock.
However if you want it you can do it. Set up the mixer as a clock master, then use the wordclock (in) connector on the uTrack24 and set the clock to wordclock. Here you can find details about the clocking