Channel-to-Channel isolation in ADC

Hello, 

Question regarding proper isolation method with following application requirements:

Voltage measurement

20 channels

Solutions for:

+-5 & +-10 V

800 & 1600 Hz sample rate

8 & 16 bit resolution

Reading from Multiple isolated power rails

High density system

EMI EN55022/32 B  or better

Reading voltage from high current sesors distributed all over, the sensors are not isolated.

I currently think that channel to channel isolation is required to eliminate ground loops and recieve true differential readings which are not cross biased through ground.

What are your opinions?