Hey Phusis. I have to give you a little support here. I have been playing my nice sound systems for about 48yrs. I have also listened to quite a few other systems and pre amps. By way of back in the day(1980-1990)doing work for some high end audio stores and hanging out in them and taking stuff home listening to it quite often using the owners and employees suggestions on what would be great to try. These places are still very active businesses.
I have had some tube pre's and solid state also. I think Jon's 'Rowland' mentioned above is quite a special one and it looks like he may know that. I happen to really like almost everything Jeff Rowland produces. Anyway I personally have all ways gone back to a passive or a passive with a what I consider a high quality buffer. All very minimalist. I have found for me going this way is more musical than any active pre(I haven't heard them all). Now when I say more musical I mean it conveys more of the sounds I am familiar with. More of the sounds meaning all of it from the initial attack to the trailing harmonics and the tonal balance. So to me (I can only guess its true but I think I have a good handle on it)I find this way more true to the natural and original sound. My background with music is when growing up I had a lot of live living room musicians to listen to. Piano, guitar-electric and acoustic, banjo, tenor sax, viola, tambourine, drums, harmonica and maybe some others. And I am also a play around guitar player. And honestly I think when you are listening to reproduced music in your living room that having live music in your living room or on the patio would give one more closely a apples to apples approximation.
I think if one has an active one would probably need to do more than drop a passive in to compare. I think you really need to pick your components for a passive system to optimize it. Just like you would do with changing any component. I say that (as many here say that the pre amp has a considerable effect and change on a sound system)because I think going from a active to a passive is one of the bigger changes one would make to a system.
I think we have a lot of wonderful equipment to choose from to provide a glimpse into the music we listen to. I am grateful for the designers and producers of our fine gear. So I also appreciate the varied views because I have only mine.
Enjoy