This entire thread has become two semantic arguments:
(1) Do rooms and other secondary sources
have a timbre, or do they
shape/alter the timbre of the primary source?
(2) Does it make sense to describe the nonlinearities and distortions of playback gear as timbre?
No, 1) and 2) are too narrow.
Some are arguing that the term timbre can be applied to the sound as perceived by the listener. I.e the sound has a timbre. (I'd say this is the broadest definition as it doesn't limit to any particular sound source).
The timbre of the sound can be considered completely independently of the source (instrument/speaker) or any transfer function that is applied (either electronically or acoustically).
Consider a blind test where the listener is not aware of the source of the sound, the room they are in or if any dsp manipulation has ocurred. Their task is to correctly identify when they have been teleported to a concert hall and are listening to real instruments playing without modification. The thing they can use to make their choice is the timbre of the sound they hear.
Clearly any factor can modify the timbre of the perceived sound. I.e. if poor speakers are used instead of real instruments, or if the listener is teleported to a bathroom instead of a concert hall.
In science and engineering it is beneficial to have narrow, clearly defined terms. (Stardards are helpful for this). However, in literature and in general conversation it allows more freedom and creativity if words are defined more loosely, or are deliberately applied in new areas and out of context. The meaning of words frequently varies over time and according to the group of people using them.
Timbre doesn't seem to be very clearly defined scientifically and is far more a word that is applied creatively (e.g. in all those audiophile reviews). That horse already bolted long ago, trying to lock it down to a narrower meaning now is not likely to work.
