So between my 220V 50Hz AC source and my 12V 5-10Amps DC load I have placed a SMPS power supply which converts 220V AC to 12V DC and is rated to supply 16Amps. Now my cable to connect the 220V AC with the SMPS power supply is rated for 6Amps. I want to understand whether it is alright or whether I would need that cable to be of a higher Amps rating. And if that is alright then how low could I go in AC Amps rating for the wire when my DC load after the SMPS power supply module continues to pull 5-10Amps DC.
In ideal situation if you have a power supply that converts 220V to 12V (18.3 times reduction) you will divide current rating by the same factor (so 16A load means 0.87A drawn from AC) In real life you should adjust that for efficiency of your power supply (it is probably higher than 80% anyway) and leave some margin for safety.
In any case your 6A cable should be plenty for this situation.