One thing that may differ from other hosts is mono panning. If you play a mono sound or mono plugin, then by default the gain is reduced by -3dB when panned in center, and 0dB when panned hard left/right. Some hosts will output at 0dB at center and boost +3dB when panned hard left/right.
i am recording the exact same tune into Reaper and Podium. same instruments, path, etc. when I put Reapers Master out to 0 and Podium to 0 there is a significantly louder volume from Reaper. it does not make sense but it is significantly louder in the other software and everything is exactly the same that i can see.
the difference is too obvious to be my imagination.
the project consists of stereo and mono tracks, mostly mono.
the wav forms look about the same in both programs.
i have put all tracks in both programs to 0 and use the master out only to adjust the total volume. seems strange to me that i would hear this much difference.
Then it’s probably because Reaper uses a different mono panning law. Try opening the Arrangement properties dialog and set the mono panning to “Balance control” (i.e. 0dB). If you have all your mono tracks panned in center, then this will raise the level of the mono tracks with 3dB.