Useful built-in macOS command-line utilities

A couple more:

    afconvert(1) - an audio file format converter, which includes Apple's superior AAC codec from the Core Audio framework

    diskutil(8) - tons of tools for fixed and removable storage

Examples:

    afconvert in.wav -o out.m4a -q 127 -s 2 -b 160000 -f m4af -d 'aac '

    mb=300; diskutil eraseVolume APFS myramdisk `hdiutil attach -nomount ram://$((mb*2048))`

Mostly I use XLD (https://tmkk.undo.jp/xld/index_e.html) for audio conversion (as I'm mostly converting from .BIN + .CUE to "iTunes Plus" AAC for uploading to iTunes Match); but my understanding is that under the covers it's mostly just using afconvert (or whatever the system-framework equivalent of it is.)

So if your needs are just "one audio file in, one audio file out, and let me tell you exactly what it should look like", then afconvert is probably what you want.