Many thanks Steve. And thanks for all of your previous contributions.
I have an Airspy, and my main reason for getting an RSP was for the Spectrum Analyser function. I was just about to buy one, when I was advised by SDRPlay that the RSP2 was being withdrawn and that a new model would appear soon. As with the Airspy, I wanted the option of the external clock input, and indeed my Leo Bodnar unit is ready and waiting on 24MHz!
The RDPDx data sheet clearly states that the Spectrum Analyser function is available, which is obviously incorrect.
If you are confident that you will be able to modify the software for the RSPDx, then I will wait. But if it proves impossible for whatever reason, I will return the unit to Martin Lynch. I will in any case notify them of the issue in case others are also misled.