It really depends on the game!
e.g. Null2's / Prodigy one is perfect for FF9 but with FFC:FF4, they have problems! Pete's DSound and the Internal one play FFC:FF4 fine!
For the Prodigy SPU (its a continuation of Null2's) I have a configuration of, 50 for the buffer size and 10 blocks!
I'm sure if you say what game you want to play then someone can give you a good config for it!
