International Class 009 (IC 009 - Electrical and Scientific Apparatus) is your best choice if you are applying to federally register your record label trademark. Your goods and services (G&S) would be, "musical sound recordings." A trademark examiner -- the government lawyer who examines your application -- may require a more descriptive listing of goods and may even suggest certain goods, for example, "pre-recorded phonograph records, and downloadable music sound recordings."
Teach a man to fish dept. There a few ways to determine the proper class. One method is to search the ID Manual at the USPTO website. Type in your goods or services -- for example "recordings"-- and the search will uncover the relevant classes. Alternatively, when you apply online for a federal trademark using the TEAS system, you will be offered the chance to search for your class (and copy and paste the information into your application). Finally, you can either find (or confirm) the right class by searching the trademark database for other companies that sell similar products. For example, we chose Basic Word Mark Searchand searched first for "Polygram" and then, "CBS Records." The registrations appeared and confirm Class IC 009. Note, record labels that also offer recording studio services may want to add a second class (IC 041 - Education and Entertainment Services).