Thank you for your help, Ivan!
I did what you mentioned, and didn’t hear any difference in the audio for either of the clips when I imported them back into Premiere Pro.
I wasn’t sure which file format to download from Vimeo, as there were 4 options:
1) Mobile .MP4 file (480×270 / 8MB)
2) HD .MP4 file (1280×720 / 50MB
3) SD .MP4 file (640×360 / 16MB)
4) Original .MP4 file (1920×1080 / 122MB
So I downloaded all of them, imported them into Premiere Pro, and there was no difference between these and the original mp4 I imported back into PP.
Thank you,
Ande