I have a 3.1 setup and the center channel helps, but it's still really bad with many mixes. If you happen to use an ffmpeg based player, and are targeting a stereo, this audio-filter helps a lot (I stole this from someone somewhere on the internet). I use it for encoding movies for car-trips (where there is both no center channel and a lot of background noise).

    aformat=channel_layouts=stereo, compand=0 0:1 1:-90/-900 -70/-70 -30/-9 0/-3:6:0:0:0