One tricky -- and often overlooked -- matter is how well the source component (say, the phono or cdp) can drive the load (i.e. the amp).... i.e. if there is enough energy and, such as this energy is, are there gross losses along the way (via the TVC interface).

One practical example: a 2V, 22ohm output cdp connected to a 10kOhm TVC, itself connected to 11kOhm amplification, doesn't seem to suffer any losses (weak bass, diminished mid-bass energy, etc).

Active pres don't have that limitation. Nor will/should they suffer from output impedance anomalies. TVCs can and do.