Just to be sure, I’m not part of the Audirvana team. This is general information.
What I understand is that you use the replay gain function on your local database. This reduces all tracks to a lower level. This reduces the chance that the signal will clip. But does not prevent it. Depending on added gain by the DSP, there may be some minimal clipping.
Qobuz does not send information about the loudness, which means that Audirvana cannot set the file to the same loudness level. Tidal does send this information. And Qobuz is working on it, as far as I know.
If this is correct then it might help to lower the total volume by 6dB. I’m not sure about this as I have no idea how Audirvana works internally. But it is possible that the 64 bit (floating point) bus is not affected by clipping. And then it’s fine that the volume is turned down at the end of the bus.
I have never used replay gain. So I have no idea what the best practice is within Audirvana. If the replay gain of Qobuz is not yet available via API then it is correct that Qobuz has a difference compared to the local library with replay gain.