Have you checked whether there is an engineering sub-menu on your TV/display that can correct for this? My Sony TV has consumer menu presets for (e.g.) default audio boost/attenuation on an input-by-input basis so I don't think it is beyond the realms of possibility that there's a (doubtless *very* terse) engineer menu that might be of help to you.

Might be worth punting this out on AVForums in the pretext of accessing the engineering menus?