(1) four speakers to expand the sound more evenly, 8-inch speakers in the mid-frequency than the ten-inch speakers more excellent and smaller volume is more suitable for small and medium-sized meeting rooms.
(2) mixer will not be used, combined machine amplifier can be inserted directly into the microphone, and then the mixer is a professional device that requires training to master the use of methods.
(3) the mixer to save money to buy a Blu-ray DVD, DVD and projector (or large LCD TV) and amplifier connection.