*As I typed this it occurred to me that IF you are playing a gig with an acoustic (i.e. a real, non-electronic) piano...you really should tune to the piano if your goal is to be truly in tune. Well, unless you know for sure that it's been tuned like within the last couple weeks and is overall still holding 440...just sayin', I know it's an unpopular viewpoint.
I recall a story here from a while back about a band that did exactly that. The gig had a house piano which was noticeably flat, so everyone tuned to the piano for the whole gig to sound "right" -- except for one guitarist who insisted on sticking to his tuner, and therefore sounded "wrong" despite being the only one technically "in tune".


