If you already have an active preamp that you're very happy with, then there's no harm in building a passive one, especially if you can do it on the cheap. I don't expect that you'll discover anything about passives that isn't already known, however. IF YOUR SYSTEM IS ALREADY TOO DYNAMIC (if that's possible), then a passive preamp might "tame" this. It will very likely sound more "transparent" than most affordable active preamps, and if "detail retrieval" is what you want more than "realistic dynamics", then GO FOR IT...I'm a firm believer in active preamps.
