Are passive preamps better?

All preamps will add a coloration. Recording Engineers know that instictively when going to grab Neve, API, SSL, Manley, etc. Most peoples experiences with passives aren't that pleasant due to impedence mismatching and the neccesity for high quality internal components. Done right it works well. My home system still uses a "dual mono" PS audio passive that I keep going back to again and again for it's sheer pleasant musicality.
If you want great sound with little thought or effort avoid the passives and pick up a Manley.

I currently run passive and here's why:

1. It squares with my system philosophy of simple, short signal path.

2. I only have a single source and don't need source selection.

3. I can't justify another set of interconnect cables, power cable, tubes, and the linestage itself. I use Cardas Golden reference cables and, while not the best, I'd feel compelled to use the same on the preamp.

So, for me, it just doesn't make sense to add another $2,000 to a system that only has $2,000 speakers, $1,200 amp, $2,500 phono stage, etc.

Interestingly, I had the Placette RVC and the "Active" which I owned between a CAT,Lamm, and now a Joule. The Placette's were excellent (we are hairsplitting between some very fine equipment), though I preferred the Placette "active"(it has no gain, but a buffer to ensure it can match with pretty much any load). Given that, I still ended with the Joule as it made the music more organic and more full bodied than the Placette approach (one of the finest IMHO); whether I prefer "distortion" or not I don't know, nor care, I'm more engaged with the music through the Joule. Maybe it is the difference between hearing into the recording and hearing into the performance - if that makes any sense.

I'm not sure if proper matching would really address what did not totally satisfy me with the passive, as the Placette Active has no mathcing issues (except possibly gain with some systems) and it was clearly better than the RVC in my system, not close in my view; it will satisfy many listeners. Experiment - but I do think the input impedance of most tube amps is proabably an important issue to good "matching".

Passive worked for me but I carefully selected a CDP and amps to match. Half volume will shake the house. First impression was incredible tranparency but that something was missing. After going back and forth between SS. tubes and passive several times, all the passive was missing in this combo was noise, distortion and embellishment.

Talk Thunder 3.1b - 4.2V XLR/ <100 ohms
DIY TVC (Bent/S&B) 0 gain
dual, bridged Plinius SA100 - over 38 dB gain
Genesis 350's - 96 dB
combined with the Genesis servo - that's a lot of wattage

A really good active preamp will actually be more transparent than a passive preamp for all of the reasons mentioned by Albert.

Using a passive preamp places demands on source components that they are often not ready to meet. Even with the rare capable source and good impedance match, a passive unit is a pure impediment or drag on the source and the signal with no upside.

I will go a step further and say that in the best systems the preamp is often more of a determining factor than the power amp in the overall sound quality of the system.