Now that is disturbing - the aspect of poor isolation.

And Erik, with a 2V full scale and 20,000 counts I think I will get 0.1mVolt resolution. And I am happy with 1mV resolution. Is that what you meant by precision ? In fact with the PCB's that we have, 12bit resolution is no problem( which is 0.48mV per bit for a 2V span) .

If 4051 is not a good choice, then is there any other better alternative ?

Thanks

Raghu