Apologies if this has already been covered.
A believe this is a good definition of audible transparency:
"Ethan Winer, an acoustics expert, states that gear passing all these criteria will not contribute any audible sound of its own and in fact sound the same as any other gear passing the same criteria.
- Frequency Response: 20 hz to 20 Khz +/- 0.1 dB
- Distortion: At least 100 dB (0.001%) below the music while others consider 80 dB (0.01%) to be sufficient and Ethan’s own tests confirm that.
- Noise: At least 100 dB below the music
- Time Based Errors – In the digital world this is jitter and the 100 dB rule applies for jitter components."
I agree with this definition, and believe it is the only sensible goal of hi-fi. Clearly, this has to apply at your chosen listening level, e.g., when your amp starts clipping it will no longer be audibly transparent.
Speakers are the component furthest from being audibly transparent, which is why many people recommend spending most of your budget on them.
Obviously, there's nothing wrong with personal preference, people differ in their tolerance to different types of distortion.
BTW, to me'system matching' (beyond basic compatibility) is about adding one kind of distortion to another to mask each components shortcomings, e.g., using bandwidth distortion to mask IM distortion around a speaker's crossover.