The LP-16 has a browser function where you have access to the files on your USB drive.
You can select the song there.
The uTrack24 is not what we are looking for. We need a playback device witth midi function, not a recorder.
The uTrack24 has MIDI output. It has the same playback features like LP-16 (even more) but it has faster access to the songs with the connected uRemote remote control