I had the same concern/question when I first hooked up the analog outputs of my Oppo BDP-103 to the 5.1 analog inputs of my Lexicon MC-12B pre/pro. I used an AIX test disc and an SPL meter to confirm that the Lexicon was applying the 10db boost to the LFE channel automatically.
I suggest you try this approach to know for sure; it is fairly simple.
Current Equipment: Datasat LS10 w/ Atmos and DIRAC. Datasat RA7300, Aerial Acoustics LR5's (LCR), Aerial Acoustics LR3's (sides), RBH in-walls (rears), Seaton Submersive, Marantz VP15s1, 106" Carada BW screen, Oppo BDP-103.