Conversation so far:
What does a Musical ensemble four part refer to
The four-piece band is the most common configuration in rock and pop music.
Who are some examples of a four-piece band?
The Who, The Monkees, Led Zeppelin, Queen, Ramones, Sex Pistols, Red Hot Chili Peppers, R.E.M., Blur, The Smiths, Echo and the Bunnymen, The Stone Roses are four-piece bands.
What four roles are there in a four-piece band?
A common formation for a four-piece band is a vocalist, electric guitarist, bass guitarist, and a drummer.
Are there alternative formations to a four-piece band besides a vocalist, electric guitarist, bass guitarist, and a drummer?
In some early rock bands, keyboardists were used, performing on piano with a guitarist, singer, drummer and keyboardist.

Question: what is a hallmark of this type of set up?
Self-contained rewrite: What is a hallmark of a keyboardist setup in a four-piece band?