Tom,
I have an SS2.2. I'll have to move it out from the back wall to get the serial number.(It weighs a short ton!) The 2.2 has a different "back panel" than the 2. Looking back, I probably got one of the last ones produced, as when I went back to the dealer a month later to get a second one, he said there were no more. It's interesting I was able to get the PX05 with a caption for use with the 2.7 speakers. (The PX02 was out of production). I have not tried it via the LTE input, although the owners manual shows the capability to connect both the passive PX and an LTE at the same time.