Dazzdax, just for the sake of friendly discussion, the purpose of a preamp is to present a proper load to the source(s), switch inputs, adjust volume and drive properly the amplifier.
A resistive passive preamp is basically made of a 10 K ohms potentiometer used as a voltage divider. The potentiometer attenuates the incoming signal.
As a load for the preceding component, it performs poorly, the 10 K amplifier input impedance in paralell with the passive preamp's internal resistance add up to an equivalent ~5-6K ohms load, too low for most CD players and even worse for phono stages.
As a driver, its average output impedance is 5 k ohms, plainly unsuitable for driving a 10 K ohms power amp* input impedance and incompatible with long or high capacitance cables.
* Most engineerring textbooks and many audiophiles agree that the preamp output impedance must be lower than one tenth of the driven component's input impedance, for optimum transfer of signal and no loss of bass/treble/dynamics. 10 K amp needs a 1 K source (or lower).
The symptoms of low input impedance (poor load) and high output impedance(poor driver) are lack of punch, dynamics and weak bass.
Also, if the ICs are high-capacitance ones or longer than 1 meter, the 5K internal impedance will form an RC low-pass filter that will attenuate treble.
All of the above is measurable and not subjective at all.
Of course there is one advantage to a resistive passive preamp: lack of active circuits, therefore one hears purer midrange and zero noise.
However, IMHO, passive resistive preamps are a flawed design and do not play music (specially rhythm) well.
Because rhythm and dynamics are so important to the kind of music that I like, I use an active preamp.
TVCs are a different ball game, they present a high input impedance to the source and a low output impedance to the load, because they are transformers.
The role of a transformer is to step up or down AC voltages (great as an attenuator) and to match impedances (great as a sorce AND a driver).
Provided that a TVC is well designed and has enough inductance, it will have no measurable frequency response roll-off from ~20 Hz to ~50 Khz. You can read the data sheets at the Steve & Billington, Sowther and Bent Audio sites.
All IMHO and IME, take my comments for what they are worth.
