The new Sonos Arc Ultra is packed with 15 amps and 14 drivers, giving the Dolby Atmos soundbar the ability to reproduce 9.1.4 channels of sound, according to the company. That’s a big step up from the original Sonos Arc, an 11-driver, 5.1.2 system. And while the increase in surround channels (from 5 to 9) and height channels (from 2 to 4) is impressive, it’s the lonely “1” in the middle of the Arc Ultra’s channel setup that might make the biggest difference.