I could try it now.
Have create a MIGX-TV and the mediasourse exactly as in the rtfm-tutorial, but did not add this TV to the template.
And created another MIGX-TV for the albumsets, which I added to the template.
The albumset-TV has this configuration (copied from MIGX-configurator-formtabs):
[{"MIGX_id":"1","caption":"set","print_before_tabs":"0","fields":[{"MIGX_id":"2","field":"title","caption":"Title","description":"","description_is_code":"0","inputTV":"","inputTVtype":"","configs":"","sourceFrom":"config","sources":"[]","inputOptionValues":"","default":""},{"MIGX_id":"1","field":"albumset","caption":"albumset","description":"","description_is_code":"0","inputTV":"resourcealbum","inputTVtype":"","configs":"","sourceFrom":"config","sources":"[]","inputOptionValues":"","default":""}]}]
And its working.