They were made at two different times, and have slightly different electronic pieces in them. 

The older one, with a slower CPU and less memory,  will not be able to run S2, and consequently would be eligible for a trade up discount. The newer one can run S2, and as a result is not eligible for a trade up discount.

I’ll be interested to see what a Sonos rep says, but so far, I’ve never seen them offer a trade up discount on a device that is capable of running S2. 

Hi @jcvessey.

Welcome to the Sonos community and thanks for reaching out to us. I understand you’re confused about why both Connect Amp does not show as both eligible. Let me help you out with that.

For the trade-up program, Not all Connect Amp and Connect are eligible for the trade-up. Being part of the legacy products means that the device we’re manufactured prior to the year 2015 and anything manufactured 2015 and beyond is part of the modern products. If only one of your Sonos Connect Amp shows to be eligible for the trade-up program, that means that the Connect Amp NOT eligible for the trade-up program was manufactured on or beyond 2015. I would recommend contacting our sales team @ +18006802345 option 4 so you can have a better discussion on what options you have and what options you can take advantage of. I would also like to share with you our Trade-up FAQ for your reference.

Please let us know if you still have further questions or concerns. We are always here to help.

Thanks,

Thanks for the help! I didn’t realize that they were different ages/versions, but I guess that makes sense (I did buy them at different times but they look exactly the same). I just added the newer (less old) one to my s2 system so will look to upgrade the other two components (the older connect:amp and the connect) and at least that will get everything on the same system again!

You’re most welcome. I suspect that at the time they upgraded the electronics inside, they had zero idea that at some point there would be anything in the future like the S1/S2 modern/legacy split, otherwise they would have named the model differently at that point. I also have to wonder if another reason it was done is the cost of the slower/smaller components became more expensive than the faster/larger electronics, and the change was made for cost, rather than other reasons, but that’s pure speculation on my part. It has made the present slightly more interesting, as you’re experiencing, but not insurmountable. Enjoy your Sonos!