How to send mix revisions a client can actually compare
Most revision rounds go wrong in the comparison, not the mix. The client plays the new version on a phone after the old one in a different app, at a different volume, from a different point in the song, and the notes that come back describe the playback rather than the mix.
Give them one link, not two files
A link that opens in the browser removes downloading, unzipping and guessing which file is which. It works the same on a laptop and a phone, and there is nothing to install or sign up for.
Name the versions the way the brief does
“mix_v4_FINAL_2.wav” means nothing to a client. Label the versions as they are discussed: “Mix 3” and “Mix 4”, or “Before” and “After the vocal fix”.
Make the comparison fair before they hear it
Match the levels so the louder revision does not win by default, and line the two up if the arrangement changed. The client then hears exactly the difference you want feedback on.
Ask one question per round
Open feedback on a whole mix produces a whole page of notes. Point the client at the change instead: “Is the vocal sitting better in Mix 4?” With both versions a switch away from each other, a focused question gets a focused answer, and the next revision has a clear target.
Trim the comparison to the section that changed, so the client does not have to find it. Thirty seconds around the edit is easier to judge than four minutes of song.
Know whether they listened
Play and switch counts tell you whether a link was opened and how hard it was compared, which is a useful signal before a feedback call.
Doing it in audiotoggle
Create a comparison, upload both versions, set the labels and levels, and publish it to get the link. Free accounts can share comparisons; Pro adds custom labels, saved level matching and alignment, play analytics, and an embeddable player for your own site.