I have a very basic question about AC coupling the output of the AD9834,
Please what is the best practice? do I put the passive high pass filter just after the output of the DDS or I have to amplify first than apply a passive high pass filter?
The second is? do I have to use small or high cap for the high pass filter? "and adjusting the resistance accordingly"
It is a tradeoff between your signal requirements output offset , gain and input offset of next stage. I would expect cap impedance should be same as source impedance at f range and much lower than load impedance. But that too is a tradeoff with low 1/f noise and signal bandwidth.