. Not quite that simple re SNRM.
On a line that easily achieves the 79999kbps sync the SNRM which is what is actually the figure reported will be higher when there is low interference such as at 4am. Then lower as daylight approaches.
On a line that does not achieve the product cap then it will always be approximately 6dB, soon on good lines 3, 4 and 5 also becoming available to DLM.
I find on FTTC mine varies very little, two or three decimal points. On ADSL2+ it was about 3.5dB
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