Our Acadia has the Entertainment pkg with the "10 speaker plus subwoofer" Bose system. For the life of me, though, I can't locate the 10th speaker. There's one in the center of the dash, 1 in each A pillar, 1 each in the 4 doors and one on either side of the third row seat. That's 9 total. Anyone know where the 10th speaker and the subwoofer are located? I'm guess they could be under the third row seat or something, but not sure...