The input for the AD7609 is coming from an inductor (secondary coil of a transformer). So without any additional circuitry, the signal would just "float".
Currently we "bias" the signal by adding a resistors to ground on each input, which also adds a (desired) load to the system.
I'm wondering if this was the right thing to do. My gut says yes, because of the high input impedance (1M) of the ADC inputs. Would it be better to have the ADC input "float" and let the ADC provide whatever bias it wants? It looks as if the clamping circuit could cause problems in such a setup. The evaluation board schematic doesn't do this though.