Yep, you're right. Sorry if I thought I'd specified the bit about the default settings and yes, you had said that bit about in-camera sharpness earlier.
I've been going through a lot of stuff these days and have had little time to devote to my camera per se. My apologies if I seem to have forgotten your advice.
However, I did find a bit of crucial info, which your last post seems to confirm: I ran some tests and it seems my D800 is either back or front focusing, so I'll need to run some more extensive tests to determine the problem and set the AF compensation.
Thanks a heap for your patience and advice (and yes, chromatic aberration correction did help).