The higher resolution the better for ADC right? Actually, it is not quite so simple. There are information I hope to have possessed before the purchase of ADS1256, which is a 24-bit ADC.

1. While 24-bit ADC can give you a good signal to noise ration,other part of your circuit, such as the op-amp rarely keep up with that level of performance. Eventually, the signal to noise ratio is determined by the noisiest part of your circuit.

2. Using 24-bit ADC require some serious know-how, since at that resolution, your PCB board itself is part of your circuit. There are tons of tricks you need to do in order to fully take advantage of that 24-bit revolution. Even for the ultimate power user, the last 4 digits of a 24-bit ADC is mostly just noise.

I might still give that ADS1256 a try. But one of my supplier offered AD7607 on sale, and it has a coaxial breakout, so I just went ahead and bought it. AD7607 is a 16-bit  ADC, should be more than enough for our purpose.