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I just installed Sonos Amp with my speakers and a KEF HTB2 subwoofer.

I see in the Sonos app I can set the phase to 0 or 180 - and I have a switch on the subwoofer that does the same thing - 0 or 180.

I set them both to 0.

My question is “why” do I have the same setting via Sonos app and a switch on the sub - and should they be set to the same setting - 0 in my case.

You have the switch on both as some subs don’t have the switch and some amps don’t have the switch. Having more than you need is better than having less than you need.

You should only be changing one phase switch, I’d start with both at 0 and listen for a while, then flip only one switch and listen some more. If the low end is better leave it switched, if worse switch it back.

You might explore other locations for your sub too, and the phase at each location to find the best setup for your room.


So they don’t need to match?


Ignore one of the switches. If you set them both to 180, the result is zero.


Look at it this way: 

0 + 0 = 0

0 + 180 = 180   or   180 + 0 = 180

180 + 180 = 360 or 0 (as 360 and 0 are the same in phase measurements)