So maybe I've got a slight bias towards duos. Aside from being a member of one, I love the energy (whether it's friction or pure momentum) of two musicians pushing themselves and each other to create music for an audience that's largely accustomed to >2 piece bands, acts, ensembles, etc. There are obvious limitations when there are only two musicians at work, and they call for more creative thinking than might be apparent. The usual concerns of songwriters are always on the minds of a duo, but dynamics, technical ability, and variety are of particular concern. It's the nature of the beast... and it's really exciting to see a duo pull it off and make you forget there isn't another musician involved.
