The obvious/tried-and-tested options are all mentioned above (ie, piano; massed strings; muted trumpet).
But another instrument that tests speakers/entire system in a very different way is the vibraphone ("vibes"). This is primarily played in acoustic jazz and/or modern percussion composition.
The layout of brass keys is piano-like, but the sound is very different: keys are struck with mallets, so you get that 1st-strike transient, followed by lengthy sustain (courtesy of sound propagation tubes beneath each key). My favorite players use 2 mallets per hand & can play many notes, simultaneously or in fast sequence.
The result is a characteristic "shimmer" to the sound. It's a louder than you think, something microphones readily react to if not set up properly.
I find that speakers & electronics that fully convey the complex sound of this instrument can generally hit it out of the park on just about every instrument.
But another instrument that tests speakers/entire system in a very different way is the vibraphone ("vibes"). This is primarily played in acoustic jazz and/or modern percussion composition.
The layout of brass keys is piano-like, but the sound is very different: keys are struck with mallets, so you get that 1st-strike transient, followed by lengthy sustain (courtesy of sound propagation tubes beneath each key). My favorite players use 2 mallets per hand & can play many notes, simultaneously or in fast sequence.
The result is a characteristic "shimmer" to the sound. It's a louder than you think, something microphones readily react to if not set up properly.
I find that speakers & electronics that fully convey the complex sound of this instrument can generally hit it out of the park on just about every instrument.