I know more than some, and less than others
It shouldn't make any difference which way you control the subs volume but I would tend to adjust it using the physical dial rather than using your receivers channel volumes. With a little practice and patience it's not too hard but is a bit of a pain dashing around the room!
Once you've got that right you can fine tune it for different surround modes if necessary using your amplifiers channel volume. I've had to increase the gain by 1dB in stereo mode for example.
In essence, it's best to get it right with the amp volume set to 0 and adjust the actual subwoofer.
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