Twenty-five members strong, the Solaris Vocal Ensemble is a testament to the power of the human voice. Dedicated to crafting a repertoire of choral music that spans time periods — think Renaissance a cappella selections alongside contemporary compositions — the Burlington-based group educates as it performs. In “Holiday Lights,” singers welcome the Inora Brass Quintet for a varied program that takes listeners on a journey around the world. Arranged for mixed voices and brass, a choral setting of the 14th-century macaronic In Dulci Jubilo complements international carols and Christmas spirituals for a memorable concert experience.