I thought the idea behind using the "unfitting" password music at the beginning was to immediately put the listener into Castlevania mode by drawing on that piece's ability to really evoke memories of the first time you loaded up CV2, and then sort of shock you out of it with the beat, eventually bringing you back with a fairly unchanged rendition of a beloved theme.
I'm not really a fan at all of mixes that deviate extremely from the original, ones that if you heard them on the radio you wouldn't even know they came from one of your favorite games, so this is right up my alley. In fact, I only registered so I could let Vic Viper know that I've literally been listening to this mp3 for years and consider it to be one of the finest versions of one of the best songs from my favorite game series. It seems sorely underappreciated here. Thanks man, and move your ass on making some more music!