Hey Markgp, welcome to the forum.
How does the waveform look in Kristal? Does it look like a pretty good sized waveform like in my attatched screenshot or does it look smaller (lower in volume)?
If it looks similiar to my screenshot, then in your soundcard's mixer window make sure the playback volume for Wave and Master Volume are turned up enough to get a good volume. Also what kind of a speaker system do you have? Does everything else (mp3's, videos, etc) play at a good volume on your computer?
-tkr