Hello, I am new to this forum and novice audiophile. I recently bought a Sonos Amp and a pair of KEF speakers for music and a television sound system. I am thinking about adding a center channel speaker to the set. The issue I am having is on the back of the amp there is a left and right terminal for both the left speaker and right speaker (see screen shot below). The center channel speaker just has a black and red terminals, I presume it wires it internally as a left and right speakers to receive the full spectrum of sound or if you purchase AV equipment at that is designed to support a center channel would have the required outputs on the amp but not in this case. On the Sonos owners manual it states that "two pairs of 8 ohm speakers wired in parallel are also supported" so theoretically I could have a second pair of speakers just fine but instead I plan to buy a single center channel speaker (1) for a total of 3 speakers and the center channel has a left and right terminal (or red and white). I'm leaning towards purchasing a 2 zone speaker switch which is supported as well by Sonos (see screen shot below) and configuring speaker pair 1 is pretty straight forward because it has a left and a right terminals for both pairs but how would I configure speaker 2, the center channel with just a a single left and a right terminal - see screenshot below?

I went online and found the diagram below but on it, the center channel speaker has 4 terminals while mine just has 2. I'm not sure how this should be wired. Any help is greatly appreciated.

 

Your amplifier is simply left and right stereo. It does not have a center channel amplifier.
A center channel speaker is usually low-fi and plays mono speech if it has a center channel amplifier..

 

Welcome to AAC.

What do you expect to come from the center channel?
How do you expect it to benefit you?

 

I was hoping for better audio when we watch movies. The kef speakers are great out loud noises but not so good at movie/tv dialogue.

 

I was hoping for better audio when we watch movies. The kef speakers are great out loud noises but not so good at movie/tv dialogue.

You could use a center-channel dual-coil speaker or two speakers close together for that purpose (assuming the amp can drive two speakers in parallel), which would give the sum of the stereo signals.
Thus the common (center channel) sound from the two stereo signals would be double the power (6dB) greater than the left or right stereo signal from one channel.

Here's a interesting configuration from the old Dynaco company, but it requires that both amps have a grounded output, and many modern amps use a bridge output, which do not share a common ground.
You can check that with an ohmmeter to see if there's low resistance between and of the two sets of stereo outputs.

 

I was hoping for better audio when we watch movies. The kef speakers are great out loud noises but not so good at movie/tv dialogue.

If you have a stereo signal, a derived middle channel isn’t really going to be brilliant. You might be able to use a decoder similar to this one*, and separate center channel amp. You’d wire it as 3.1 (without the subwoofer). It would get the real center channel signal. Left and right would be the FL and FR channels using the amp you currently have.

*Not an endorsement, I don’t know anything about this particular product.

 

I agree that using a surround-sound decoder as Ya’akov suggested would likely give you the best center-channel sound, if you don't mind adding an extra amp.
The problem is controlling the center-speaker volume along with the stereo volume.
You would likely need a decoder with a remote volume control.