Thanks for that info.
I checked, and the problem MP3 files do have values in the analyzer data.
Examples:
Fleetwood Mac, World Turning, ripped from CD to WMA lossless: Volume Level (ReplayGain) 2.60 db, Volume Level (R128) -2.4 LU, etc.
The Zombies, Time of the Season, downloaded from Amazon MP3: Volume Level (ReplayGain) -5.26 db, Volume Level (R128) -10.3 LU, etc.
When playing back (through Media Library DLNA to Xbox360 to Denon AVR via HDMI), the Zombies song is way louder.
The XBox 360 profile in Media Library options is set to Mode: Specified output format, Format: PCM 24 bit, Stereo downmix checked, volume leveling checked, Sample rate 48,000 hz
The Denon AVR shows audio status of 48K, 2.0 channels.
When playing back on the PC using JRiver player, the two songs have similar volume levels. Under audio, I have volume leveling and adaptive volume checked.
Maybe I don't understand how this is supposed to work.
Thanks in advance for any suggestions...