First, I want to thank the developer for creating this tool, it's very useful.
I noticed during use that the results obtained for mono MP3 files differ from those produced by other tools.
The scan results with fb2k_with true-peak scan plugin:

The scan results with EZ CD Audio Converter:

The scan results with rsgain:

As you can see, the results from fb2k and EZ CD Audio Converter are the same, with a loudness of -26.21 LUFS.
However, the result from rsgain differs by about -3 LUFS compared to the other two.
1ch.zip
First, I want to thank the developer for creating this tool, it's very useful.

I noticed during use that the results obtained for mono MP3 files differ from those produced by other tools.
The scan results with fb2k_with true-peak scan plugin:
The scan results with EZ CD Audio Converter:

The scan results with rsgain:

As you can see, the results from fb2k and EZ CD Audio Converter are the same, with a loudness of -26.21 LUFS.
However, the result from rsgain differs by about -3 LUFS compared to the other two.
1ch.zip