Answer
Thanks for your interest in the P-45. We've included excellent quality speakers in the P-45 - these are designed for home practice and work well in living rooms, small studios et al and can be used to accompany a solo vocalist (without a microphone) for instance.
For accompanying choirs or playing with other instrumentalists, we'd recommend using an external stereo speaker system. The PHONES/OUTPUT socket of the P-45 allows you to connect the P-45 to a stereo PA system for instance (for pianos with dedicated professional outputs, look at our P-115, P-255 or CP Series stage pianos).