Thanks for the quick response, but no!!
I have WAV files and understand it can only read WAV, but there is no option just to play the track once the SD card is back into the console.
If you go to the home screen, capture, you get to the new session/load session screen.
Load session will take you to any session you have created on the SD card using the recording feature.
You do not see any files you have added yourself. and I have tried creating folders and folder structures as the others created by the console.
I have got around it by recording a few seconds into a new folder. then replacing the WAV files with the WAV tracks I have but keeping the name of the WAV files created.
This is very clunky - would be good just to add a folder with Stereo Wav Files in and be able to pick and choose to play any of them.