Cue + Replay Gain

 % eix -S 'replay gain'
* media-libs/libreplaygain
     Available versions:  477-r1
     Homepage:            https://www.musepack.net/
     Description:         Replay Gain library from Musepack

* media-sound/rgain
     Available versions:  (~)1.2.1-r1 {flac mp3 vorbis wavpack}
     Homepage:            https://bitbucket.org/fk/rgain
     Description:         Set of programmes and Python modules to deal with Replay Gain information

$ wavegain --help
WaveGain v1.2.6 Compiled Jan 12 2018.
Copyright (c) 2002-2005 John Edwards <john.edwards33@ntlworld.com>
Additional code by Magnus Holmgren, Gian-Carlo Pascutto, and Tycho

 Usage: wavegain [options] input.wav [...]

 OPTIONS
  -h, --help       Prints this help information.
  -a, --album      Use ReplayGain Audiophile/Album gain setting, or
  -r, --radio      Use ReplayGain Radio/Single Track gain setting(DEFAULT).
  -q, --adc        Apply Album based DC Offset correction.
                   DEFAULT is Track based DC Offset correction.
  -p, --no_offset  Do NOT apply DC Offset correction.
  -c, --calculate  Calculates and prints gain settings, and DC Offsets BUT
                   DOES NOT APPLY THEM - This is the DEFAULT.
  -x, --scale      Writes scale values to stdout in the format: n.nnnnnn
                   In Album mode it only writes the Album Scale value, and
                   in Title mode it only writes the Title Scale values.
                   ONLY works in Calculation mode.
  -y, --apply      Calculates and APPLIES gain settings, and applies
                   DC Offset correction.
  -z, --recursive  Search for files recursively, each folder as an album
  -l, --log        Write log file.(Default filename = WGLog.txt)
  -f, --logfile    Specify log filename. (Assumes -l if present.)
  -n, --noclip     NO Clipping Prevention.
  -d, --dither X   Dither output, where X =
               0   for       dither OFF (default).
               1   for       dither without Noise Shaping.
               2   for       dither with Light Noise Shaping.
               3   for       dither with Medium Noise Shaping.
               4   for       dither with Heavy Noise Shaping.
  -t, --limiter    Apply 6dB Hard Limiter to output.
  -g, --gain X     Apply additional Manual Gain adjustment in decibels, where
             X = any floating point number between -12.0 and +12.0.
                   Clipping Prevention WILL be applied UNLESS '-n' is used.
  -s, --fast       Calculates and prints gain settings - DOES NOT APPLY THEM.
                   NOTE: This method does NOT process all samples, it only
                         processes 200 x 16k chunks of samples. Results will
                         NOT be as accurate as a full analysis but, with most
                         material, will be within +/- 0.5db. Files of 8,192,000
                         real samples, or less, will be analysed in full.
                         DC Offset is neither calculated nor corrected in
                         FAST mode.
  -o, --stdout     Write output file to stdout.
 FORMAT OPTIONS (One option ONLY may be used)
  -b, --bits X     Set output sample format, where X =
             1     for        8 bit unsigned PCM data.
             2     for       16 bit signed PCM data.
             3     for       24 bit signed PCM data.
             4     for       32 bit signed PCM data.
             5     for       32 bit floats.
             6     for       16 bit 'aiff' format.
         NOTE:     By default, the output file will be of the same bitwidth
                   and type as the input file.
 INPUT FILES
  WaveGain input files may be 8, 16, 24 or 32 bit integer, or floating point
  wave files with 1 or 2 channels and a sample rate of 48000Hz, 44100Hz,
  32000Hz, 24000Hz, 22050Hz, 16000Hz, 12000Hz, 11025Hz or 8000Hz.
  16 bit integer 'aiff' files are also supported.
  Wildcards (?, *) can be used in the filename, or '-' for stdin.

$ shnsplit -o wav -f you.cue you.flac
$ wavegain -r -l *.wav
$ rm -fv *.wav
$ cat WGLog.txt
$ nano you.cue