Many of them have very good sound quality, the majority even, but the more I listen the more I'm realizing that the collection is rough around the edges. A lot of mastering is really just normalizing the volume, making everything listenable and polishing the eq. It's not meant to fundamentally change how something sounds, that's typically done in the engineering/mixing phase. There are a number of tracks in this collection that are too loud (20 Vtnm), too soft (Bellbrk), and then there are the ones with crazy highend frequencies that hurt my ears (17 Alis Trak). The older tracks tend to have more volume and frequency problems and the newer ones seem to be more consistent.