Passive preamp

When I hear passive preamp, I’m thinking of a unit that does not amplify the signal halves, but the quality of components, power supply type as in diodes or tube based rectification, in addition to capacitors, etc will leave its fingerprint on music. I have an Esoteric C-03X preamp that is able to add +6, +12 or +18 dB on the output side. If I choose the 0 dB setting, this is somewhat like a passive preamp as the signal halves do not pass through any amplification/processing. Next, the signal is influenced by the power supply quality as in transformer size, quality and selection of caps and resistors will influence the sound as it passes through the preamp so it is not just an attenuation nob with resistors linked to it. At the 0 dB setting, music seems less embellished, well at least not processed by an op amp or something similar; the music has an open and airy sound. When I choose +12 dB or the higher setting, bass extension and the transient snap is better, plus bass is deeper and denser; overall, the music seems to be faster, which I’m guessing the bit of processing increases decay. This would make sense as Esoteric’s output board has a brace of capacitors to give music that transient "snap." I choose the Goldilocks setting, meaning the middle setting. Although, Ottmar Liebert on the passive 0 dB gain setting is pretty amazing...