I unboxed the Arc Ultra expecting to like it and to immediately reach for the matching sub. I never reached for the sub. The new Sound Motion woofer in this bar is the first time I've heard a soundbar produce bass that I'd describe as authoritative rather than approximate. F1: The Movie and the engine-room scenes of Evil Dead Rise had the kind of low-end punch I associate with adding a separate subwoofer, except there wasn't one.
The channel layout is real. Fourteen speakers in a 9.1.4 arrangement, powered by fifteen Class D amps, and unlike most up-firing-only Atmos bars, the height effects on this one actually place themselves. The helicopter in the opening of Top Gun: Maverick passes overhead rather than diffusing into a vague upward smear. On standard 5.1 mixes, this is a good soundbar that gives you clean dialogue and a wide front stage. On real Atmos content, it's the only single-box bar I've heard where the surround illusion is convincing enough that I stopped paying attention to it.
Dialogue clarity is the second standout. The center channel is clean even in dense action mixes, and the Speech Enhancement mode has multiple levels rather than the on/off switch every other bar gives you. I left it on Low for most TV and bumped it to High for late-night episodes where I couldn't turn the overall volume up. It works.
Now the things that will bother you. There is no DTS support. If you have a 4K Blu-ray collection with DTS-HD Master Audio tracks (which is most physical-media libraries), you'll be re-encoding or routing around the bar to get the audio you paid for. This is a Sonos position rather than a technical limitation, and Sonos has held it for a decade. If it matters to you, this is the wrong bar; if you stream everything, you'll never notice.
There is also a single HDMI eARC port. No console passthrough, no second HDMI input. The Sonos position on this is that the TV does the switching; the user position is that I had to add an HDMI switch in front of the TV to keep three sources untangled. Annoying. Not a deal-breaker.
The Sonos app remains the open question hanging over the whole product. The infamous app reboot of mid-2024 left a lot of long-time owners furious, and while the app has stabilized considerably, I had a setup hiccup on day one that required two restarts before the bar showed up. Once configured, it's been rock-solid. The trust deficit is real, though, and if you've been burned before, the Arc Ultra inherits that history.
At $999 USD, this is the most expensive single-bar Sonos and the most expensive Arc, and the original Arc is still excellent and frequently on sale. If you have an original Arc that's working, the upgrade is real but not urgent. If you're starting from scratch or coming from a much older bar, the jump is meaningful.
Verdict: Buy this if you want one box and no subwoofer, and you don't have a DTS-heavy disc library. If you do, look at the Samsung HW-Q990D.