I used to think passive preamps were superior to active preamps given right the setup, but

I do not normally get in on these type of conversations but the facts are everyone is correct.
Passive is the best interface sonically, least parts to hurt the sound.
BUT
If the device cannot drive the load (input impedance) of the next device (usually amplifier) properly then a preamp or a product with current gain is necessary to drive the input load and get the best sound (performance) of the device being driven.
To overly simplify one product drives the next if you do not have enough voltage or current than passive will not sound as good.

With regard to Nelson Pass' commens

I have a 1996 version of his Pass Labs Aleph P preamp that has separate controls for gain and volume. His advice was to set the gain as low as you can and the volume as high as you can for your basic listening and use the remote to adjust the volume.

I've gotten the up-grade itch several times, but have yet to find anything I like better. Amps and speakers have changed but the Alpeph P has been a constant.

To be totally successful in using a passive-pre the rest of the system must be built/chosen with the accomodation in mind. This doesn't really require compromises IMO since the things that work best also make for a better system.  In such a case gain can only be detrimental to the sound since any active device with gain will also surely add colorations to the sound.
I've been using the passive approach most of the last 30 years.  For the last 15 it's been TVC/AVC based devices. I've occasionally tried promising low gain active designs up to $5K but have always come back to the TVC's purity and quietness. 

The best preamp is no preamp?...  Possibly... but only if the recording was perfect and recorded in an ideal space with phenomenal room acoustics.   Otherwise?  I still prefer Technicolor movies over the plain variety. I know..  Not real... But,  so much more pleasing and stimulating to your soul.  After all, that is why we seek to listen to music! Recording engineers know this.  That is why they will often times add effects and enhancements to what was recorded. 

I learned my big lesson when I began op-amp swapping with my high quality pre-amp/phone amp.  No piece of equipment is neutral.  Even the passive ones. For there are various kinds of passive preamps that produce different sound!  So? Create your own "neutrality" of sound.  One that produces a believable sound that YOU THOROUGHLY ENJOY.   Not one we are to be told is enjoyable but does not quite move you. It always has to be quality - low noise - design. That never varies.
 C'est la vie.