Don't know of a study, but awhile back I talked to a manufacturer's rep at a local Mom & Pop HT store and he said that in Europe audio was most important over video...60% audio vs 40% video. That in the US it was opposite...60% video and 40% audio.
Jeff
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976/7125/OPPO BDP-83
NHT 2.5i's main, NHT Superones Side/Rear, Mirage OMNI CC center
2 M8 subs, Harmony 650, OAW3
Samsung 60" 4k
Outlaw 970 still works great(just decided to finally upgrade)