-31dbf is what you want. So setting it to -9 in Soft Encode sounds right. The reason it sounds so quiet is also explained in that thread (if you're referring to the one I think you are). Basically when the audio is transferred from the theater to the home theater, the wide range of sound can only be reproduced accurately if the whole level is brought down. You have to turn up your amp, and the result is that big explosions and such sound good while faint sound effects are still audible.