Normalizing using RMS as opposed to Peaks.

[DJDemon]

I have many FLAC files ripped from CDs I have collected over the years. It is a diverse collection of both Rock and quieter melodies. I am using Audacity to get them to a common level without the use of ReplayGain, as the player in my vehicle, although it plays FLAC, no one is able to tell me if it can use ReplayGain adjusting, on playback, in real time.

There is a Replay Gain Plugin for Audacity. Take a look at ReplayGain plug-in
The plugin will adjust the actual audio data to get the volume right, so you won’t need a player which understands any Replay Gain tags.
The plugin is not perfect, yet better than anything that is based on RMS alone without taking human perception into account.
Just stay with the default volume setting (89 dB); it’s unlikely that you will need additional compression to avoid clipping.

Or, alternatively…

Convert the tracks to mp3 and run them them through the “mp3gain” progam. In your vehicle the superior quality of FLAC will - most likely - not be perceived, anyway. Pro: Much faster than method 1; it needs no manual interaction.

just my 2c
Walter