How to A/B compare two mixes or masters fairly

To compare two mixes fairly, match their loudness first (louder almost always sounds better), then switch between them at the same moment in the song rather than starting each from the top. Listen in short sections, on more than one system, and write down what you hear at a time in the song so the next version fixes it.

Five steps

Match loudness. Turn the louder version down until both feel equally loud.
Same moment. Switch in place; don't restart the song.
Short sections. Loop 10 to 20 seconds and switch several times.
Several systems. Monitors, headphones, a phone speaker.
Notes at the time. “1:42 vocal up” beats “vocal a bit low”.

What to listen for

The lead: is the vocal or main line always clear?
Low end: kick and bass sitting together, not fighting.
Width and depth: does anything disappear in mono?
Energy: does the chorus still lift?

Common questions

Why does the louder mix always sound better?

Our ears hear more bass and treble as level rises, so a version only 1 dB louder can seem fuller and clearer. Match loudness before you judge.

Should I compare whole songs or sections?

Sections. Loop the chorus or the drop and switch back and forth; memory of sound fades within seconds.

How many versions should I keep?

All of them, named in order. The one you threw away is often the one the artist liked.

Can I compare against a reference track?

Yes, with the same rule: same loudness, same section, quick switches.

Or A/B it in Songcase

Songcase keeps every version of a song in order. Its A/B plays two versions together and switches between them at the same second and the same loudness, so you hear the mix, not the level. Notes sit on the waveform at their time, and can be on one version or all of them. Songcase is free to start. Keep every version organized.

How to compare two versions of a mix