If the system is working right, it shouldn't matter. Instruments located exactly where a speaker is should sound like that instrument, and others place elsewhere(whether center between the speakers or outside the far edges)should to. With a top flight system, you should also hear depth in the location of sounds, with some instruments deep behind your back wall, others even with the plane between the speakers, and many in between. The best systems will simultaneously portray instruments even forward of the speakers if that's what's on the recording(not quite as common). If any of this is news to you, you need to hear some other systems at a dealer or another audiophile's home. Cheers,
Spencer
Spencer