My usual issue with volume in my movie room is one of too much. I have efficient speakers powered by a powerful amp in a room that is a tad small. I used my RadioShack meter to set the individual speaker gains to 75db with my volume indicating -16 db. When I watch a movie I adjust the volume to around -16db indicated. For the most part that is extremely loud for action movies and loud enough for my old ears for dramas with lots of dialog. You should get a SPL meter to determine the actual sound pressure in your room. RadioShack makes a cheap version and there are also Apps for your phone which can be used. Bear in mind that the accuracy may not be absolute but it is a relative measurement.
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Music system
Model 990/7500/Magnepan 1.6 QRs/Technics SL1200 MK2/Aperion S-12 Subwoofer/OWA3/Sony NS75H DVD
APC H15 Power Conditioner

TV System
Large Advent Loudspeakers/ Polk center/Monoprice surrounds/Panasonic Viera 42 inch/Onkyo HT-RC260/Sony BDP S590/Directv


Home Theater System
Onkyo PR-SC886/Outlaw 7125 Klipsch RF-82 L/R,RC-62 center, RB-35 SR/SL, BENQ HT1075, Outlaw LFM1-EX/OPPO BDP-83/Directv
Harmony ONE
Blue Jeans and Monoprice interconnects
APC H15 Power Conditioner