There are certain rare evenings when the walls between centuries dissolve, when the spirits of long-departed composers seem to hover in the air, nodding with approval as their intentions are realized with breathtaking authenticity. From the moment one opened the elegantly designed program booklet, it was clear this would be no ordinary concert. With their 19th-century accoutrements and historically accurate construction, the ACO’s commitment to period instruments transformed familiar works into vivid new sonic experiences.