Pubul57 -- I would put it that an active gain stage (which as you realize is required if gain is to be greater than one) will inevitably have at least some tiny amount of various kinds of distortion, and a passive preamp will inevitably have at least some tiny amount of impedance matching issues.
But good design of the active stage, and proper application of a passive preamp (short cable lengths, high input impedance of the component it is driving, etc.) will in both cases make the issues audibly insignificant based on known science.
Which does not necessarily mean that they will sound the same, given for instance the claims by many audiophiles that audible differences can be perceived even between different brands of high quality resistors, between different orientations of the fuses in the back of the equipment, etc.
While I would consider some (but certainly not all) such claims to be not well founded (translation: nonsense), it seems clear that known science and known forms of distortion cannot explain everything about the differences we hear between audio components.
Regards,
-- Al
