Independently means you can select a different sound as you wish for the different sections of the keyboard. If you choose to play the keyboard in split mode as this is the best sounding method for full band effect, you can split the keyboard into two sections. The left section is for bass (for example) and the right section for your main voice and a layered voice. For DGX300, you cannot choose a different voice for the bass section. In fact you can only choose from a combinations (pre-selected) split voices - i.e. the factory already pre-assign a bass voice and piano voice combination and you cannot change it. What if you want to change the piano voice with a brass sound while maintaining the same left hand bass voice - well, you cannot !!! However, I think you can change them independently for DGX202 and PSR292 - but then you are missing the registration memory capabilities.