To build on that, if you are planning to buy the KABD-4100, that board has the amplifier built in. There are a couple different ways to accomplish this. If your TV doesn’t have RCA outs, sometimes it has a headphone plug. If you buy a cable that splits out from the headphone to two channels, you can then buy the RCA termination and wire it to go from one to the other. Double check what input plugs come with the KABD-4100 first. I’ll dig out the accessory pack later today. But you can wire up the board to whatever termination you would like, including RCA. You then would just wire the output from each channel of the KABD-4100 to each driver.
Now, if you do not have headphone out or RCA, then I agree with @elliottdesigns that toslink/spdif would be next. since you are doing stereo, practically any hdmi audio extractor should do it. And he is correct, if you do not have a receiver or similar, then you have either the ARC (audio return channel) on the TV (check the manual) or you will need a splitter and then one goes to the TV, one to the audio extractor, then to the KABD-4100. Also, if you want to use a remote for the volume, then you would need to get a device to put in-between the extracted signal and the KABD-4100. You can only control the volume over bluetooth when you are streaming bluetooth music to the device that I know of (playing with the JAB5 from Sure/Wondom). That will act like a pre-amp. An Arylic Up2Stream with a remote and RF extender module should work wonderfully for that purpose. Also, you can connect that to the internet and stream to the speakers that way, allowing for more use than just for TV. But that uses the plug termination like for headphones, so you could do a headphone out from a tv to the arylic, then that headphone out over to the KABD-4100, then out to the speakers.
Since you haven’t started yet, take your time. Do not rush this. Pick out everything that you would need or want in the audio chain. Research each type of termination that is used (later today, I’ll tell you what the accessory pack includes for input for the KABD-4100, but I can guarantee it is not RCA in, so you would have to wire it for that). After figuring out every device, look up wires and terminations on amazon or whatever other retailer where you can find the terminations to do that with. Decide if you will buy something to house the electronics or 3d print or how you want to do that. Because that will help narrow down thinking how you will have to mount the terminations to wire it all up.
Once you know every termination, everything that needs wired, how you will mount it, the enclosure, etc., then buy the components. But don’t buy first then change your mind like I did. I have a couple JAB5 I’ll use in future products now, but that is a couple hundred sitting idle. I might put them in some bookshelves for my nieces in the future or something.
Hope that helps a bit.
Also, the splitting happens at the TV, generally. That then gives you PCM or other standards out, or uses the ARC. That way you know, the sound bar isn’t splitting it unless you plug into the soundbar first and then the soundbar to the TV. I don’t think there are many products that do that these days, but could be wrong. Many soundbars with HDMI in use the ARC from the TV. But check your manuals, it should tell you.