The problem with randonly jacking up volume so all trakcs are the same is that you can loose sound quality from chopping off frequency ranges.
for a score fan like me, this can muddle louder sounds and chorus, remove the openess and breath of a peice, cause distorition in louder levels, and if it's something older it can raise the hiss level.
If you don't care about that, you can always get a program like Audacity (you'll need to make some changes in the settings for quality purposes), loaded the track that has the volume level you want, select the whole track and try to raise the volume. If it says you can only raise it, for example, 1.5, then remove the track and load every other cue seperately and raise their respective volume only there is only 1.5 left.
However, if you don't have a good sound card, it's not worth it. A cheap sound card can not only cause errors, but if you wanted to record something, a cheap sound card won't give you the options to mute channels like the microphone, so there will always be an underlining hiss.