Hi Daniel,
You can do this by creating a custom contact list in Qualtrics for all of your participants, which would include their participant ID, maybe a passcode, and then the name of their song. For example, it might look something like this before you import it into an actual Qualtrics Contact list:
Of note, you need to ensure that your participant ID is related the "ExternalDataReference" variable.
Once you have imported your contact list, you can set up an authenticator element at the top of your survey flow-- participants login to the survey using their participant ID (and password too, if you want):
Then, directly under the authenticator, set up an embedded data field by selecting "Add a New Element Here" and then "Embedded Data":
From there, go to the "Add from Contacts" option at the bottom right of the embedded data element and select your contact list from that menu.
Then select "Song" and hit "Ok":
Then, information should pop into the embedded data field in the survey flow like so:
Apply the changes to your survey flow when you are done. Now, the information on the participant's song will be brought into their survey.
Lastly, just use

${e://Field/Song}

Thanks a lot!