When it comes to music, "tune down" typically refers to lowering the pitch or volume of a musical instrument or singer. However, there are many synonyms for this phrase that can be used in a variety of contexts. Some possible alternatives include "dial back," "lower," "soften," "subdue," "moderate," "temper," "restrain," "curtail," "diminish," "deescalate," "minimize," "downgrade," "adjust," "calm," "relax," "mitigate," and "lessen." Each of these words can convey a slightly different nuance or meaning, depending on the situation and intended tone. Overall, however, they all signal some form of a reduction or dampening effect.