What makes a master player?

What makes a master group?

Can anyone recognise the skills of a master?

Can anyone recognise the sound of a "master group"?

What are people who organise festivals/venues looking for: masters or crowd pleasers?

Are masters always crowd pleasers?

Are masters masters of their instruments, performance, teaching, communicating, charismatising (new word) or are they just good at PR and have a good promotional machine behind them?