Figure 38 in the datasheet for the AD9208 shows converter power over sample frequency, but only goes down to 2400 MS/s. Is there any data down to 750 MS/s?
Interpolating the power graph, we assume the digital and driver power is relatively constant and the analog power will go down linearly. This leads to a guess at ~2.5W when using it around 750 MS/s. Does this seem valid at a high level?