Yamaha's installation series speaker address a number of important issues that give them unprecedented performance and handling characteristics for live sound applications, including permanent installations. In particular, phase characteristics have been kept smooth and consistent throughout the entire series, so you can mix and match speakers to suit any system and venue without ending up with hot and dead spots due to phase interference. And of course sonic quality is superb throughout the entire reproduction range so the full impact of the source material reaches the audience undiluted.