See the same Wiki page regarding the LFE loss: "The Meridian 6 channel SPDIF inputs are treated as "Music6" and will therefore apply the Music speaker layout. The default "Music6" preset will be applied when the source is selected. This will be the "Discrete" preset unless changed in MConfig (so you should change it to Cinema or you'll lose 10db of LFE on Movies)."

You probably just need to se the preset to Cinema.

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