Volume levelling too quiet

[Kabukiman]

I've been leveling the replay gains of all my tracks to 0dB, because the relative volumes of each track can be jarring to say the least. While this has given the tracks a more consistent volume overall, they're consistently too low. I don't know very much about how it works, I don't know if the issue is that I have both "on track basis" and "on album basis" ticked, I don't know if it's that I've been levelling the tracks in small groups and not every track at the same time, or if it's that I'm keeping them levelled to 0dB, which seemed like the right place to keep them since it's directly in the middle. I usually keep the volume bar in the app at its highest setting, which is lower than it is for other apps like Spotify and Deezer. I don't know if it's because I have "normalize volume of tracks with replay gain tags", and I've disabled it just in case. Is this referring to a compression of the audio within a track itself, or is this referring to maintaining a similar relative volume between tracks?

[hiccup]

Yes, the loudness leveling feature tries to set the perceived loudness of a track/album to the level you have set with the slider.
If you find that resulting in your music sounding too soft on average you can move the slider to a higher value.
You can check the replaygain tag of a song to see if it will actually get played louder or softer than intended.

[SkyZippr]

The target loudness of ReplayGain utilities is 89 dB SPL with the silder at 0 dB. Such value was chosen (not by Musicbee, but by the author of ReplayGain) to avoid clipping during playback. Since most music nowadays are generally much louder than that, your music will in turn sound quieter with ReplayGain on.
As hiccup said, you can check the value in the properties tab. For a typical post-2000 pop album, the volume leveling would be -7 to -9 dB.

[frankz]

If all of your tracks have replaygain and most of the replaygain values are in the normal range (-7 to -9 would be a treat. Most recent pop I see are in the -9 to -11 range TBH), then you can use the equalizer in MB to bump up the pregain a little bit to compensate for the reduced leveled volume.  I have mine at about +3db.

It would be nice to have a "prevent clipping" setting on the pregain and also a "with replaygain value / without replaygain value" there, but my +3 has been a good compromise and I haven't cared enough about it to wishlist it.

[Kabukiman]

If all of your tracks have replaygain and most of the replaygain values are in the normal range (-7 to -9 would be a treat. Most recent pop I see are in the -9 to -11 range TBH), then you can use the equalizer in MB to bump up the pregain a little bit to compensate for the reduced leveled volume.  I have mine at about +3db.

It would be nice to have a "prevent clipping" setting on the pregain and also a "with replaygain value / without replaygain value" there, but my +3 has been a good compromise and I haven't cared enough about it to wishlist it.

What if I just set the volume leveling to +3 for the replay gain? I want the volume tagged to the files themselves so I can have a consistent volume when I sync to my phone, etc.
Also, I don't understand the clipping warning. I had some files saying it needed to be, say, -0.2 or -0.8, but I set them to 0dB and the error went away. Why did the error go away when I didn't set them as low as it told me to? If a track needs to be -0.8dB, does that mean that raising the volume past that in the equalizer will make them clip?

[hiccup]

I had some files saying it needed to be, say, -0.2 or -0.8, but I set them to 0dB and the error went away.

It means 'adjust by', not 'set to'.

[frankz]

What if I just set the volume leveling to +3 for the replay gain? I want the volume tagged to the files themselves so I can have a consistent volume when I sync to my phone, etc.

You can do whatever you want, but my advice is to get standardized, accurate readings for your files so whatever program you may use on whatever platform now or in the future will know what to expect and then correct to taste at the playback level. 

Any Android music player app I've ever used on my phone (GoneMAD, PowerAmp, Neutron, Foobar) has had a preamp setting (I may be wrong on this next part because don't remember each specific feature of each player, but I think each of them also had separate "with/without Replaygain" values and prevent clipping features on their preamp settings, too).

[hiccup]

The target loudness of ReplayGain utilities is 89 dB SPL with the silder at 0 dB. Such value was chosen (not by Musicbee, but by the author of ReplayGain) to avoid clipping during playback.

Good info.

Only a small correction on the technicalities:
MusicBee doesn't use the (ancient) ReplayGain algorithm (2001) but the much more advanced EBU R128 algorithm.
And R128 uses LU instead of dB, where the '0' on MusicBee's loudness scale equals -18 LUFS.

For the question asked by the OP it's probably not that important, but it's probably good to be correct on the underlying technical details and mechanisms.

[lilies_of_the_void]

The thing that solved it for me was switching output to "WASAPI (Exclusive)" under Edit->Edit Preferences->Player. It does come with the consequence of no other sound sources being able to play while using MusicBee, but that is worth it for me.