"lowpass" is valued only when "subwoofer mode" is 2.1 or 2.2 , For 2.0 mode, "lowpass" can hidden.
Important, if "subwoofer mode" is changed, unit must be rebooted.
Default value: lowpasss: 90 subwoofer mode: 2.2
Piano 2.1 has one more setting "subwoofer volume", this can be change with the "digital volume".