For Windows Vista/7, try adjusting the sound device settings. Right-click on the speaker icon in the Windows task bar next to the time, choose "Playback devices", select the device you are using in GoldWave, choose "Properties",
choose the "Advanced" tab, then select the default format that matches the file's bits and sampling rate. Also try
turning off the "audio enhancements" option.
If audio plays too fast and is distorted, try using DirectSound mode in GoldWave. Press F11, choose the System tab, then choose the DirectSound button (Windows Vista/7 only).
Try playing the file in other software, such as Windows Media Player to see if the quality is low as well.
If you are working with 8 bit files, then low quality unavoidable. See "Dither" in the GoldWave help.