A torture test for any of these machines is the opening credits for The Descent on Blu Ray. If you can fix it on this scene, you’ll have no problems anywhere else.
for me, brightness to 49 (which strangely gives more shadow detail at near black levels) and contrast enhancer on low. Since changing these settings, I’ve not experienced any banding at all.
Urgh looks like I will have to watch that one day then. Its on my shelf to remind me I'm not a spelunker.