Pro Audio is used as a term to refer to audio equipment as well as audio engineering applications. These applications include sound reproduction for small venues as clubs that could range for 50 to 500 people, medium venues such as outdoors events ranging from 500 to 2500 or large venues such as concerts ranging from 2500 to 200,000.
Professional Audio Equipment can be described as any audio equipment used for sound application. This equipment would include microphones, mixers and signal processor for live performances as well as, recorders/playback devices for reproduced performances. These applications will also use power amplifiers, more processors and speakers to provide for these applications. Pro Audio equipment typically carries a higher quality and additional features compared to home audio or consumer level audio equipment.
Professional Audio Applications are referred to as professional audio engineering and operations, which could include broadcasting in a radio station, audio mastering in a recording studio, sound reinforcement for live performances, audio sampling, public address and piped music.
Sound Reinforcement Systems is the combination of microphones, signal processors, mixers, amplifiers, and loudspeakers that makes live or pre-recorded sounds louder and may also distribute those sounds to a larger or more distant audience. A sound reinforcement system is also used to enhance the sound rather than just amplifying a sources that is unaltered. This could be a very complex system that includes a full mixer of microphones, complex mixing and signal processing, several thousands watts of amplification and multiple loudspeaker arrays or stacks all overseen by a team of audio engineers and technicians. My focus, as a hobby, are the small to mid-size systems for venues of 100 to 1000 in size for live music.