In which section must you adjust the envelope to change the sound of a sample?

To change the sound of a sample using an envelope, the amp section is the correct choice. The amp section typically includes controls that allow you to adjust the amplitude envelope of the sound. This envelope is crucial in shaping how a sound evolves over time, affecting parameters such as attack, decay, sustain, and release.

By manipulating these settings, you can create various sound dynamics, such as making a sound hit sharply and fade out quickly, or giving it a slower attack for a more gradual build-up. This is fundamental in sound design and music production, as it allows for nuanced control over how samples are perceived within a mix.

In contrast, other sections like modulation, loop, and effects focus on different aspects of sound processing. The modulation section deals with parameters that modulate the sound over time but does not primarily adjust the amplitude envelope. The loop section is concerned with creating seamless repetitions of samples, while the effects section applies audio effects, such as reverb or delay, rather than shaping the core envelope of the sound. Hence, for envelope adjustments, the amp section is indeed the most relevant area.