Can you point to any evidence that shows that the output from a DNG file is in any way different to that from it's original RAW when both are processed in the same way with the same RAW converter?
The original question in that form was not really relevant, i.e. this is not the real issue; nor is that post on DPreview relevant regarding the main issue.
DNG is (supposed to be) partly a format change of the original data. Although the encoding adopted by DNG in the compression is the same one adopted in CR2 files, there are small differences. The differences are greater with Nikon compressed image data; spme other formats are totally different.
The only relevant questions
1. if the image data remains unchanged or directly (i.e. one to one) convertible between the native format and DNG,
2. if all relevant info is converted or saved in DNG format.
Condition 1 is fulfilled mostly but not always
. The exceptions are worthy dio be discussed on their own;
condition 2 is fulfilled by savng MakerNote in the DNG file.
Note, that I discounted the option of saving the entire original raw data in the DNG file
, for that is plain garbage
Back to the subject: it is NOT important, that the same result be generated from the different formats. DIfferent versions of any raw converter may yield different results from the same raw file, no matter which format.
It is important to understand, that the DNG file contains not only the "natural data" (i.e. that, what is taken from the native raw file) but its interpretation is added
. Particularly, the color reproduction is an issue, which is entirely in the domain of the raw processor and can be changed. Thus there is nothing strange on the fact, that different versions of ACR or of the DNG converter generate different outputs.
Again, the main issue is, if the raw image data remains the same except for formal changes. The example I provided demonstrate, that this is not always the case. That error has been removed, but all related images converted from NEF in DNG format in that period are permanently lost
if the NEF was not kept.
I repeate it: only computer illiterates would believe, that any software, no matter from which corner it comes, is guaranteed error free and one can blindly trust to throw away the original data