I tried out several Passives over a weekend and was very surprised
how different they were. For some reason, I thought being passive would make them sound similar, no way at all. It was two years ago, so I can not remember the brands, but the Music First Audio Baby Reference was way ahead of the other three. Very clean and neutral, with as good detail retrieval as I've heard. Yes even this expensive unit lacked the last ounce of dynamics, but what was there was still very good.
A version two of the Baby Reference is out, so the original should be a bit cheaper, if you can find one. A passive is one unit I would buy second hand. It won't last for ever, but it should be pretty indestructible.
