could be your pads. I sell auto parts for a living and it seems like we get more returns on raybestos parts than the shitty cheap chinese made junk we offer. but yet again, raybestos products are now mostly made in china too. if it were me id change the brake fluid then see what happens. The quiet stop pads are most likely a ceramic pad desgined for being quiet and low dust.
look into the "advanced technology" pads if you lake raybestos. they are designed for more severe duty like on cop cars, ambulences etc...
Mark
1999 M3 Cosmos Black/ Black 78k
1994 540i Oxford Green/ Silver Grey Sold @ 133k
1995 M3 Arctic Silver/Black Sold @ 117k
1990 325i Zinnobar Red/Black Sold @ 115k