Using the ACW to equalize tempo is unnecessary, unless the source song doesn't follow an exact tempo. If the tempo wavers even slightly then it's necessary to use the ACW, either to set up the tempo map or to equalize the tempo.

If your song follows an exact tempo, all you need to do is align beat 1 in BB. To do this, go to the Audio Edit window and select one of your audio tracks. Left click to drop the cursor at the exact point you want bar 1 to start at, then right click and choose "Mark this point as bar 1 of the song". Then change to each other stem track and do the right click part again without left clicking anywhere.

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