There is a separate setting for xo and sub for 2 channel mode. Go to the advanced playback menu, then 2 channel mode, then turn it on and set xo and LFE.

You have to turn on the sub manually in PD. Put the AVR in PD, and press the "CH Sel/Enter" button on the AVR (it's the center button of the directional buttons). Scroll down to SW, and turn it on to the level you like.

LFR1100 Actives,QS10HPx2,QS8x2,EP800,M3x4,M3x2 (Wood),M5HPx2 (Wood),AxiomAir,ADA1500-8,ADA1500-7