I tried installing Armbian before I got Coreelec running and it was no go.
I did not know the dtb files were kernel specific and could not be interchanged. I am happy enough with Coreelec so will stick with that and have now flashed the sdcard to the emmc. Thanks for your replies.
Out of interest....even without a correct dtb file, should I have seen some kind of attempt at boot activity albeit with errors? I couldn't get passed anything more than a reboot loop or just a black screen?