ADC Isolation

[Anatoliy]

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 sensors distributed all over, the sensors are not isolated.
each sensor provides at least one, ac or dc signal, and a return line.
signal cables are a few meters long.
I currently think that channel to channel isolation is required to eliminate ground loops and receive true differential readings which are not cross biased through ground.
What are your opinions?

[robertferanec]

I am not expert for analogue

PS: If it would be possible, I would probably try to place a small AD circuit as close as possible to the sensors and then used cables to transfer digital data to the central unit.