Just an observation really that I noticed some time back.
My third multi tuner is set to cable and the SNR is always low, it fluctuates between 55 and 63.
At first I thought it might be the cable or connector but if I put my OS Mini in place of the Mega then the SNR is 98 to 99.
It this low because it's a multi tuner and not a dedicated tuner.
Thanks.