... a good YouTube video can go a long way, and while you’ll never portray all the nuance, you will hear anomalies in the response and get a good idea of what the system is capable of ...
YouTube uses lossy audio - not unlike mp3 files - and it sounds like it. The visual component adds no value. YT just can’t tell you much about how a system sounds. Of course many people are happy with lossy audio. Just look at the popularity of Spotify!