Hi Peter.

From my experience, there was only a brief period when it was fashionable to mike each instrument in the quartet separately, in order get enough separation to adjust the panning. It was generally considered more appropriate to record the ensemble from a suitable distance using a crossed stereo pair of microphones. This of course, necessitates having a room with suitable acoustics, which isn't as important with close miking, but it does mean that the positioning of the instruments isn't quite as crucial.

Whilst the the purists insisted on a crossed stereo pair, the popular music fraternity would sometimes use a spaced pair of mics to enhance the stereo effect, with the distance between the mics controlling the amount of effect. For a pronounced effect PZM boundary mics would be placed on the side walls of the room.

Hope that you find at least some of this useful.

ROG.