Lucky, good find on the JC2! I've got the A21 with a P7 from Parasound. I concur with auxinput that you only use the Main outputs of the JC2 for the A21.
Hopefully you have XLR cables to go from the JC2 output to the a21 inputs? They look like this:
https://www.amazon.com/AudioQuest-Diamondback-audio-cable-stereo/dp/B000ETSYUK/ref=sr_1_3?ie=UTF8&am…
Also, could you list what brand speaker and RCA cables you are using now?
Hopefully you have XLR cables to go from the JC2 output to the a21 inputs? They look like this:
https://www.amazon.com/AudioQuest-Diamondback-audio-cable-stereo/dp/B000ETSYUK/ref=sr_1_3?ie=UTF8&am…
Also, could you list what brand speaker and RCA cables you are using now?