The Best Preamp is no Preamp?

Agreed!  Even gooder is eliminating power amps (technically).  Music server feeding Weiss 501 DAC/volume control directly to ATC active speakers.  Faster, more dynamic, more detail and only four pieces to reproduce music.

Since Enlighten Audio Design (EAD), Theta days in ‘90s.. fast forward to dCS Verdi/Elgar/Purcell/clock to more recent days’ Accuphase 2 boxes, and friend’s Vivaldi stack, MSB Select (complete) double power bases, pre module etc, Esoteric Grandioso stack—still I/we found running through preamps the sound were just more realistically ‘live’ and musical (bluntly~akin to 2D vs 3D rendition of the music). Unless one wants to simplify, or $ave on peripherals (cabling etc.), a great preamp in a top flight system is the way to go.

Maybe someday in the future when pre module in dac or passive improved further can hopefully forgo the pre, but not yet.. imho, ymmv.

I’m digital only and currently using only one input on my preamp, yet it costed more than my speakers—yes call me crazy, but the difference (to me) is rather dramatic and worth its cost.

I've always used the CD-direct-to-amp as a sanity check for evaluating how a new preamp sounds.  The direct is always more neutral, but lacks a certain "something".  A lesser preamp will clearly sound worse than direct, but a good preamp will tend to sound bigger, wider, & more dynamic.  I've had a couple pre's that were switchable between active & passive, and I found it interesting to switch between modes.  The passive mode would be more neutral, but I usually left it on active.  Over years and years of use, you'd think I'd just instinctively gravitate towards the position that gave me greater pleasure, and that position was always "active".   

A passive pre will allow you to listen to your power amp. If you like what you hear, that may be all you need.

If you don’t like what you hear, you might need to add 2nd harmonic distortion to the signal (active pre) to fatten up the sound, add body and dimension, texture....the good seasoning us audiophiles tend to crave.

If your DAC isn’t 2 volts or you have really long cable runs, an active preamp may be required.

I've found over the years that a really good preamp seems to provide to me the best results sonically.  These days, most source components have good output drive, and preamps end up being more attenuator than amplifier.  However, the signal still goes through the preamp's amplification stage and depending on the quality of those components that touch the signal along with the power-supply can provide drive to the amplifier(s), especially with long lead lengths.  Some amplifiers need fairly high input voltage for full output and the input impedance of some amps may require a more robust source signal which is where a great preamp will be better able to drive it.    Yes...  The preamp will add in its own sonic signature (color if you will) but in my experience, has resulted in the best sound for my listening enjoyment.  Obviously, there is no simple answer for this question !  It's basically the exquisite dance of specific components and how they play together for your personal sonic enjoyment...