The answer to the question: "Who's in charge here?" is quite simple.
If there is a musician in the group, it would be the musician.
And, it doesn't even have to be a music setting.
Musicians tend to be "take charge" sort of people.
Musicians tend to be...yes, I'll say it...control freaks.
We like being in control of the situation, especially when it relates to a musical situation.
Think, if you will, back to an experience you might have had in a choral or band ensemble.
Directors of these ensembles are (should be) very much in charge. They control not only the musical direction of the ensemble, but also the general atmosphere and attitudes of the ensemble's members.
A strong, confident director leads and inspires students to be strong, confident musicians.
A weak, uncertain director leads and inspires students to be weak, uncertain musicians.
As I look back over those who I have had the privilege to make music under their batons I see strong, confident directors. I was certainly blessed to be under their tutelage.
Their influence on me as a musician, a teacher, and a conductor is obvious. I have often caught myself doing something in the classroom or on the podium and realized "_______ used to do/say/etc. that!"
Now, young musicians, it is important to remember to project the qualities of strength and confidence in the classroom and on the podium. Doing so does more to exude control than demonstrating the "freak" aspect of the phrase "control freak."
So, rather than brag about being a control freak:
Focus more on building your strength and confidence as a musician, as a teacher, and as a director.
The control will be perceived and respected.