FOR SINGERS
If you’re a singer, you really need to hear your own voice loud and clear, so you don’t strain your voice. But you also need to hear the instruments because you need a solid pitch reference to make sure you sing in tune. You also want to hear and feel the rhythm so you can keep your singing in the groove!
FOR INSTRUMENTALISTS
If you play an instrument, you want to hear what you’re playing loud and clear so you don’t wear out your fingers, and so that the subtleties of your playing matter. But you need to hear the vocals to keep you in touch with the structure (and the emotion) of the song; and you need to hear the drums so you not only play in time, but groove well with the group.
FOR DRUMMERS
If you’re a drummer, you want to hear the drums well enough to have an accurate sense of your balance within your kit, and so you can feel the impact of your kick and snare. You need to hear the bass in order to function well as a rhythm section; you need to hear the vocals to help keep you oriented in the song structure; and you need the energy and rhythm of guitars and keyboards.