So far I played movie from prime video.. Before adding power amp, watching movies with prime used to get to single digit volume like -9 dB and I would be hesitant to push the volume more..So I refrained going beyond a particular MV of the AVR..
After adding the power amps, with no tweaks to speaker levels, at MV at -10dB feels more than enough for streaming lossy audio..
With lossless audio tracks in BR Rips, am yet to check, but pretty sure I don't have to go to single digit MV.. Even if I wanted, I know for sure that I can push it comfortably, but it gets really loud..