Our goal with this new way to upload files is to offer the most flexibility possible, allowing individual instrument selection. That way, drum players, on one hand, could choose to isolate only the drums, combining other sounds in just one other track. Producers, on the other hand, could choose to separate the song into all instruments available to get cleaner samples.
While selecting the main instruments, such as bass and piano, is unlimited, other instruments have extended options that cannot be combined. For example, the main instrument, “Guitar,” has the following extended options: combined guitars, Acoustic and Electric Guitars, and Rhythm and solo Guitars. You can only select one of those.