The nit is not the correct unit, SI metric system defines the level of Luminance in Candela/m² or cd/m². Macquarie Dictionary Photometry (in a given direction, at a point on the surface of the source or the receptor, or at a point on the path of the beam) the luminous flux leaving, arriving at, or passing through an element of surface at the point, and within an element of solid angle divided by the product of the solid angle and the area of orthogonal projection, measured in candela per square metre." The Nit is the same value. The cd/m² is measured by a spot photometer which must contain a lens to focus the light on the sensor. As a result the screen must be far enough away to keep the light in focus.
There is not any point in 10 bit luminance signal unless the display is bright enough for the white and light colours. You cannot make the screen absorb light to increase the contrast range. 8 bit signals were designed for cathode ray tubes, but new displays including projectors are much brighter enabling the use of 10 bit R, 10 bit Green and 10 bit blue. Remember that RGB signals only exist in picture generating equipment, and within the display, and in professional up and downscalers to convert the different colour primary standards.
The white and black in the image are not designed to be maximum and minimum digital values. This is because it is a hard clip which causes patches of white or black with no detail. The range is reduced to give a safety margin. For 10 bit is 040 hex for black not 0 and white is 3AC not 3FF 3FF is all one's.
Anywhere else, interconnections are in pure digital form are luminance and a pair of chrominance signals. This applies to the for mentioned signals.
It sounds as if your Brisbane antenna is one designed for channel 2 is more sensitive to interference than a band 3 only antenna for digital TV from Brisbane. There is little point in searching for the source of interference since there is an alternative source of the same programs. You need to prevent the receiver from giving preference to the Brisbane version of the Southern Sunshine Coast signals. When you scan for signals, the receiver starts at the lowest channel ie channel 6 which is before channel 29 which must be ignored. This is why I suggested the rescans. If you want to test it without going on the roof, on the second rescan keep the antenna disconnected until the receiver has finished scanning channel 12.
Although it is late, I have just tried to update my Denon AVR X3200W. Technically it is the 29th of August and it did update to a later firmware, I don't think it was the DTS X capable firmware. I have no DTS X titles to try, but no neural x option is available to add to dts titles. Has anyone else tried to update their Denon receiver lately?