A radio like what is on the Wing,and can be controlled by the controls on the CTX.
I removed the Autocom which was fitted to my Wing,and was thinking I would fit that to the CTX and not use the Bluetooth system.
The CTX doesn't have wires so anything you'd like to add has to be Bluetooth.
Having said that, as I mentioned in a different thread, the audio box itself does appear to have (unused) connections for both an extra input and output but they are not documented and neither is the way to switch to them.
We'll have to wait for aftermarket to come up with something or for somebody with too much free time on their hands to hack their way into it