Proper impedance matching and making sure there's enough current available for good dynamics seem to be the two things an active preamp is most useful for. I've used a transformer based passive for about a year, and have been very happy with it. I just got a Morrison ELAD, which is a quite inexpensive ($780), well-made active preamp with two inputs and two outputs. It has dual volume controls and a very nice separate power supply, but no other features. My early experience with it in my single-source system is insanely positive.
Is Preamp overkill for me?
I'm a single-source guy - SACD Player. Current setup runs source to integrated but, am considering upgrading to separates (preamp/amp). Regarding preamp, I'm thinking I really just need something to control the volume. I don't need/want balance or tone controls and don't need to switch sources. I don't mind spending money ($2k) on a preamp but would rather put that money towards quality than features I don't need/want. Any thoughts/suggestions?