SDL's audio engine is fine. DirectSound is strange API-wise and requires special programming in order to get decent performance because Microsoft painted themselves in a corner and won't break backwards compatability.

ASIO is better (both in performance and in programming), but requires special licensing on Windows- including the promise not to publish your source code.

Finally, you don't have to use SDL's audio engine, and you don't have to give up the rest of SDL in order to use something else. Use SDL, and if it causes you problems on Windows, rewrite your audio loop to do things the DirectSound way.