FWIW, because of Johns comments, I must say that I've used passive's with tube amps and can't say that I ever found anything about them that made them preferrable to a good active amp.
Its too easy to lose the sources dynamics because of poor matching of cables and IC's with a passive, and like every thing else in the hobby, everything between the source and speakers is either additive or subtractive. There ain't anything that is just neutral to the source, if for no other reason that you can never know what the source sounds like with out adding equipment to decode the contents of the recording. Doesn't that initial playback equipment define neutrality.
Has anyone actually listened to the recording over the studios playback system to get a fix on what it should sound like? Perhaps a recording engineer might, or some one at the recorded event might, beable to rely on aural memories if they actually heard it, but I doubt it
I doubt that anybody would recognize 'true neutrality to the source' in audio equipment so why not add an active pre-amp to those things one might use to dial in their version of neutrality or replication of the sound of a 'live' or 'close to live' event. Do what sounds good/realistic/neutral to you! Thats what everybody else is doing. Even the guys that wear hair shirts, even though they would proclaim otherwise! :-)