All,
Not all emulators are designed the same. I addresed the reason why Jabo's DirectSound does not work in the current 1964 in the release notes. Without getting too technical, it is an incompatible implementation. You might recall that a certain old version (0.8.3) had suport for this plugin, but as a consequence it suffered from random freezes and slowdowns. This was due in part to us changing 1964 a bit to make it compatible with this plugin.
Azimer is hard at work on a new HLE plugin. In the meantime, if you have a fast machine, you can use the rsp plugin with the basic audio plugin for better sound in games where audio skips.