I'm trying to use the ADS1298 for an EEG rather than an ECG but to get the best noise figure possible, I'll have to add some extra gain at the front. I was planning on using instrumentation amplifiers and feeding the single ended signal output and A/D reference voltage into the PGAs on the ADS1298. Is there a better way to go about this? I'm just worried about digital switching noise on the power lines affecting the reference voltage. Should I be using a fully differential amplifier instead of an instrumentation amplifier?