I use WAVmaker from Polyhedric Software. It does'nt go via the soundcard, but uses sampled instrumental patches to render MIDI files directly into WAVs. The quality of the resulting WAV files is superb - better than I can get with my AWE64 soundcard - and no hiss.

From what I remember WAVmaker is free to download, but you only get a minimal number of patches. When you register it they send you a complete set of patches.