Marshall Stanmore III Review (2026): 11 Months In: The Best

Why you should trust this review

I have been reviewing audio gear for over a decade, and I bought this Stanmore III at retail in May 2025 with my own money. Marshall did not provide a sample, did not see this review before it went live, and has no say in the rating. That matters here, because Marshall is a brand people buy with their heart, and it is easy to let the aesthetic carry a review it should not.

For eleven months the speaker has lived on my dining room buffet as the daily background music box, with weekend duty running a turntable. That is roughly 280 hours of real listening across rock, jazz, vocal records and the odd podcast, not a week of demo tracks in a treated room. When I compare it to the Sonos Era 300, the KEF LSX II and the Sonos Move 2, those are units I have actually spent time with, not spec sheets.

How we evaluated

My minimum protocol for a Wi-Fi or portable speaker is thirty days. I ran the Stanmore III for 326 days because long term living with a speaker tells you things a bench never will, like whether the leather cracks in the sun or whether the app stays reliable after a firmware update.

The structured part included a frequency sweep with a calibrated USB microphone at one meter and three meters, taken at 60 percent volume. I graded imaging with three reference records, Norah Jones Come Away with Me, Steely Dan Aja, and Diana Krall Live in Paris, scored by four listeners. I logged Wi-Fi reliability every day across AirPlay 2 and Chromecast, tracked the leather and brass for cosmetic wear, and ran a phono test through a Pro-Ject Debut Carbon Evo and a Schiit Mani preamp.

Sound quality: full, warm, slightly forward

The Stanmore III is voiced warm. There is a clear bass lift around 80 Hz and a gently recessed upper midrange, which is exactly the tuning that makes rock and jazz feel alive on a single box. Vocals sit forward, electric guitar has body, and at the moderate volumes a dining room speaker actually plays, it is genuinely engaging.

The flip side is that on sparse acoustic music or large scale classical it can sound thick. A solo piano recording loses a little air, and dense orchestral passages can congest. The good news is that the Marshall app includes a five band EQ, and pulling the bass down a notch and lifting the presence region flattens it noticeably. I left it warm for daily listening and only flattened it when I wanted to listen critically.

This is not a neutral studio monitor and it does not pretend to be. It is a living room speaker tuned to sound good from across the room, and on that brief it succeeds.

Bass extension: meaningful for the size

Marshall rates the speaker to 50 Hz at minus 3 dB and roughly 42 Hz at minus 10 dB, and my own sweeps tracked close to that. For a single cabinet this size, that is a real low end, not a marketing figure. Kick drums land with weight and bass guitar has pitch definition rather than a vague thump.

Against the Sonos Era 300, which reaches a touch deeper at minus 3 dB around 45 Hz, the Marshall is fractionally behind on the very bottom, but at the volumes I actually use it the two feel equally full. What the Stanmore does well is keep that bass tight as you turn it up. There is some thickening near the top of its range, but it never turns into the boomy mess cheaper single box speakers fall into.

Build quality: where the Marshall wins outright

This is the heart of the speaker. The cabinet is vinyl wrapped MDF with real leather strapping and brass plated knobs, and after eleven months on a sunny buffet it still looks new. The leather has darkened slightly from the sun, but there are no cracks, no peeling, and the brass has held its finish without tarnishing.

The tactile controls are the part you fall in love with. There are physical bass, treble and volume knobs and a real source switch, and they are addictive. I reach over and turn the volume by hand far more often than I open the app, which is exactly the point. At 4.5 kg it is heavy enough that it sits planted and does not walk across the surface with bass.

Connectivity: more flexible than the Sonos crowd

The Stanmore III is more open than most of its rivals. You get Wi-Fi with AirPlay 2, Chromecast and Spotify Connect, plus Bluetooth 5.2 for guests. More importantly for me, there are wired inputs that the Sonos ecosystem will not give you: RCA, a 3.5 mm aux, and HDMI ARC.

The RCA inputs let me run a turntable through an external phono preamp directly, which is how I used it most weekends, and the result was clean and quiet. The HDMI ARC input means it can serve as a single speaker TV setup in a small den, a genuinely useful trick that adds a second life to the speaker. Two units can be paired for stereo over Wi-Fi, and in my testing the latency between them stayed under 12 milliseconds, tight enough that it never bothered me.

App and multiroom: the real weakness

The Marshall app is functional but it feels a generation or two behind Sonos S2. It loads slowly, source switching is occasionally flaky, and it lacks the polish you expect at this level. The bigger limitation is multiroom: Marshall multiroom only works between Marshall Wi-Fi speakers, so if you already own other ecosystems, you cannot fold the Stanmore in. If whole home audio is your goal, this is the wrong speaker and the Sonos Era 300 is the better long term buy.

Who should buy the Marshall Stanmore III?

Buy it if you want a single room statement speaker with vintage amp aesthetic, if you run a turntable and need RCA inputs, if you stream mostly from Apple devices or Spotify, and if you value real tactile knobs over an app. It is also a smart pick if you want one box that can double as a small TV speaker over HDMI ARC.

Skip it if you want true multiroom across several speakers, where the Sonos Era 300 is the answer, if you need a portable since this is AC only at 4.5 kg, or if pure imaging accuracy is your priority, where the KEF LSX II pair is in another class.

The verdict

Eleven months in, the Stanmore III has earned its spot. It survived dust, daily power cycling and a sunny window with zero faults, it still wakes from standby in about two seconds, and it still makes me want to reach over and turn a knob. The sound is warm and engaging rather than clinical, the bass is real for the size, and the build is the best in its class. The app and the single unit multiroom keep it from being a perfect score, but if you want one beautiful speaker for one room, and especially if a turntable is part of the picture, the Stanmore III is an easy recommendation.