BladeRF direct sampling via RXOUT pins (Common Mode Voltage / input impedance)

I’m trying to get the direct sampling going on the bladeRF (lms6002). What does the chip expect on the pins for the RXOUTP / RXOUTN for signal? I hooked an amplifier up and with a blocking cap was able to receive a couple of SW stations, but nothing really substantial. I googled and I could find no answers here.