If you understand the principle that the original recording can't be made any better (you can't add information) to the signal then audiophiles should know that no recording studio uses boutique expensive cable. So cables that are more expensive than the original recording studio or production cables are illogical. Where am I wrong? "
Where are you wrong? You are wrong as follows. You start what would generally be considered as statement of fact i.e. you cannot add information to the original recording. You then follow this with a statement that is a combination of a conjecture and an argument from authority fallacy viz "then audiophiles should know that no recording studio uses boutique or expensive cables. You then attempt to conjoin these two statements to suggest that (the use of) cables more expensive than the cables used for the original recording is illogical. This is a non sequitur fallacy because there is no causal relation between your two statements.
The reproduction of recorded music is an entirely different act to the recording of the music. While one may not be able to add information to the original recording one can take many steps to retrieve the information that is there. This is the whole premise of hi fi.
Your argument implies that because recordings are made with components of a particular level of quality, then using better quality components to reproduce them is pointless. That argument is specious for the reasons set out above.