I think his point was that in the context of a preamp (or any other component) transparency usually is a good thing. Bad stereo equipment homogenizes sound and makes different recordings sound similar.
If a recording is bad, the better audio equipment will let you know that. If it doesn't then by default it also means that good recordings sound less good then they would through a more transparent piece of equipment.
If a recording is bad, the better audio equipment will let you know that. If it doesn't then by default it also means that good recordings sound less good then they would through a more transparent piece of equipment.