Devialet with waterfall niagara part of surround set

[ogs]

It seems like the pre-out on the Denon is giving a low signal. The Owners Manual does not say anything about the level here.
To adjust, first disable Audyssey, then find a suitable level for front L&R relative to the other speakers. The Vrms value is related to Denon's max pre out signal level. Setting this value lower than 2 is not dangerous, you only risk overloading the Line in on the Dev. You'll hear it as distortion if/when the Denon in turned up to play very loud (more than 1 to 2 o'clock is my guess). It might be better to set the Devialet to 0 dB and use less gain on the Denon, but what sounds best here IS best....
Re-run Audyssey calibration to fine tune the multichannel setup afterwards.