RedKong: Yes, those two programs do not make an intermediate .wav file. They can normalize the volume across the entire album. In particular mptrim can automatically remove the silent part at the end or the beginning of a song. I have bought the game and I found out that the soundtrack is the same low quality version that can be found on file sharing sites. The first six tracks are ripped from the Bonus DVD of the Collector's Edition and as such have good quality. The remaining tracks are to a large extent low volume, low quality files with popping and static noises. Some tracks have up to 4 minutes of silence at the end (like track 70 "the last obstacle"). I have used the programs above to make it a little less jarring, but GOG could have asked for a higher quality version of the complete soundtrack, I imagine someone at ubisoft must have it.
Vainamoinen: Thank you VERY much for the info. Because for that OST quality, I really won't buy this game again. :(
geez, wish I had read this before purchasing PoP 2008 today, very annoying popping noises on almost every track I have listened so far, how did this disgrace slip through GOG's quality control?
EDIT: just wrote to GOG support team to let them know about this issue, also noticed that the noises seem to affect tracks 7 to 40 only (out of the 81 available).