My engineer friend wants to hear samples of a tube limiter I own and I want him to be able to pick out all the fine details. I want to send him a song with reasonable levels we both know by heart so we can communicate the differences between the dry, and altered track.

We both own legal physical copies of the song and the album it's from. The download is only available to him, and will be destroyed once he receives it.

Give it to me straight!

as long as it's noncommercial, and not available to the public I can't see why not.

Cool. I did it, and I think I hear the sirens!