In the performance of post-production tasks, we sometimes export the same audiovisual content, with the same container format, in two different audio configurations:
A two-channel stereo version (L-R) to be used for example from studio playback applications.
A four-channel stereo version (L-R / L-R) to be used in the continuity / broadcast system, typical of the Digital Terrestial Television format.
Within this process we have verified that the 4-channel version suffers a decrease of 3 dB with respect to the audio levels of the sequence from which it was exported, a decrease that in the case of exporting to two channels does not occur.
That is, if we export a reference tone modulating at -15 dB, in the case of the 2-channel version it will maintain that level, but in the 4-channel version all tracks will modulate at -18 dB. This fact occurs regardless of the room or equipment that is used.
In Adobe Audition there is a Preference setting for the Default Panning Mode for this issue, iow to make exports not to to export with a 3dB decrease but there is no equivalent setting in Premiere Pro. The workaround some use in Premiere Pro is to just add 3 dB to the master to compensate.