Hi-Fi ADJUSTMENT is a job that involves adjusting the TONE of audio equipment to ensure optimal sound quality. This is done by using specialized tools and techniques to adjust the frequency, volume, and other aspects of the sound. The term HI-FI ADJUSTMENT is derived from the acronym 'High Fidelity, ' which refers to the highest quality of sound reproduction. The crossword solutions for this term are TONE, which refers to the frequency of sound waves, and ADJUSTMENT, which refers to the process of making changes to the sound.