Did you ever get control of the AR with the software or did you switch to something else?Hi, probably does not help you but been playing with getting my old AR5000A going again with a panadapter. I matched it up with a ELad FDM-S2 SDR I have, it seems to work okay but no control of the radio which I would like. However I did notice the software has specific settings for AR8600 control as part of the Advanced settings, Special Modes for use with 10.7mhz input.
Still playing with it and learning so will see what can be done with it. I also saw a video with again a AR5000 10.7 output feed into a SDRPlay SDR and working.
Sorry no experience with AR8600 nice gear tho, good luck!