To apply or not to apply (replay gain)

  • 14 September 2023
  • 3 replies

I stream good-quality 320 kbps MP3 music files from a Synology DS120j to a Sonos Beam (Gen 2) with Sub Mini using the Sonos app. We are full-time RVers, but when we had a house I used all FLAC files via a Logitech Squeezebox Duet, a good class A/B amplifier, and some high-end transmission line speakers. Obviously, there’s not room for that stuff in the RV! Anyway, I’ve recently learned that replay gain can be applied to files to even out the volume levels of the listening experience. I’ve downloaded Foobar2000 and explored the replay gain function, but I’m not completely clear on file vs. album (and whether or not “album” can mean every file on the server) replay gain - and some of the numbers from the analysis don’t look right to me. Can the group enlighten me on this topic - how to go about it and the pros/cons? I have recordings dating from the ‘60s to the present… folk, folk-rock, some eclectic stuff, and all the way up to contemporary artists and recordings - but no classical. Just for background, I’m a former musician with what used to be a very good ear, but I’m loosing some of my high-frequency hearing as I age (all too common, I’m afraid).

Thanks in advance!



Best answer by ratty 18 September 2023, 11:37

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Hi @Rob_L 

Thanks for your post!

I’m not familiar with Foobar2000, so the amount that I can help is limited. All I can really tell you is that the metadata field that Sonos will look for replay gain values in is REPLAYGAIN_TRACK_GAIN.

My posting here will get this topic back on the list of those recently active, so perhaps more help will be forthcoming.

I hope this helps.


Around 15 years ago, when I originally ripped my CDs to FLAC, I ran the whole lot through Foobar2000. Those REPLAYGAIN_TRACK_GAIN tags are still present and Sonos does take note of them. Sort of.

As I recall, there are limits to the adjustment it will apply. Nothing greater than +/-10dB and, based on some long-ago experiments and discussion here, the +ve gain is somewhat reduced (halved maybe?) from what’s expected.

Album gain is not supported at all. 

There used to be a support article on volume normalisation but it’s been pulled, presumably because the implementation is, er, a bit incomplete.

Ah, I’ve just noted that the OP states that the files are in MP3, not FLAC. To be honest I don’t know whether Sonos supports REPLAYGAIN_TRACK_GAIN in MP3. 

It might be simpler to run the files through MP3Gain. This modifies the volume scaling factor in each MP3 frame, so its results are effective on any media player. It’s reversible, as the raw music data is untouched.