A Tube and a Transistor that superseded it, both have specific role to play in a topology belonging to the signal path, there is a sonic trait that can be described as being quite similar to both of these designs when the Topology and Circuit Design is well executed.
As a result of the limits to the role a Valve or Transistor is to fulfill, there is a detection of a difference to a sonic, when compared to a more modern design that is using parts such as Semi-Conductors that have superseded both Tubes and Transistors.
The Semi-Conductor has a multi-function role, which is specified through circuit design, to more than one role in a topology. It is this multi-role that has a noticeable sonic trait in comparison to a Tube or Transistor Amplifier.
It could be said the more the Semi-Conductor is competing for the multi-function within the working circuit, the more the Sonic Trait from the part in use is noticed.

