This answer applies to R7 Mk1
Increasing the bass level in the EQ settings also increases the subwoofer level. The reason for only having negative adjustment on the subwoofer is so if R7 produces too much sub bass in a particular location, then reducing the level should allow a well balanced sound to be achieved. When all parameters are set flat the sound balance should be about right for most environments, but allowing the bass to be lifted and the subwoofer level to be decreased should allow an ideal balance to be found for most rooms.
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