Whenever the lead singer/songwriter in a two-person group steps out with a solo album, the first question that comes to mind is whether the musician needed to go out on his own, whether he could possibly be constrained by his lone partner. In the case of Dan Auerbach, the guitarist & singer for the Black Keys, it's not so much that Pat Carney holds him back as that he's such a distinctive, powerful drummer that he colors & changes Auerbach's playing; it's what band chemistry is all about. Op