The Marshall Stanmore III and the Sonos Era 300 cater to different listening preferences and environments. The Stanmore features a classic design with tactile knobs for volume, bass, and treble adjustments, delivering a warm, rich sound profile that’s particularly engaging for genres like rock and blues. It connects primarily via Bluetooth 5.2, along with auxiliary and RCA inputs, focusing on straightforward, high-quality audio playback without built-in smart features.
In contrast, the Sonos Era 300 adopts a modern, innovative approach with an hourglass design housing six drivers, including upward-firing speakers, to support spatial audio and Dolby Atmos content. It offers extensive connectivity options such as Wi-Fi 6, Bluetooth 5.3, AirPlay 2, and USB-C line-in, integrating seamlessly with voice assistants and the broader Sonos ecosystem for multi-room audio setups. While the Stanmore III emphasizes simplicity and traditional aesthetics, the Era 300 provides advanced features and immersive sound, appealing to those seeking a more technologically integrated listening experience.
Specs Comparison
The Marshall Stanmore III delivers 80W of power through a two-way system, featuring a 5-inch woofer and two outward-angled tweeters. This setup provides a warm and balanced sound profile, particularly suited for genres like rock and blues. Connectivity options include Bluetooth 5.2, RCA, and a 3.5mm AUX input, focusing on straightforward, high-quality audio playback without built-in smart features. Its dimensions (13.78 x 8.00 x 7.40 inches) and weight (9.37 lbs) make it a solid yet manageable presence in a room.
In contrast, the Sonos Era 300 takes a modern approach with its unique hourglass design, housing six drivers: four tweeters (one upward-firing, two side-firing, and one forward-firing) and two woofers. This configuration supports spatial audio and Dolby Atmos content, creating an immersive listening experience. The Era 300 offers extensive connectivity options, including Wi-Fi 6, Bluetooth 5.0, AirPlay 2, and a USB-C line-in (with an optional adapter), integrating seamlessly with voice assistants and the broader Sonos ecosystem for multi-room audio setups. Its dimensions are slightly larger (10.24 x 7.28 x 6.30 inches) and it weighs 9.85 lbs. The Era 300’s sound profile is adaptable, benefiting from Sonos’ Trueplay room correction technology, which optimizes audio based on the room’s acoustics. This results in clear and detailed sound reproduction across various genres, with a notable emphasis on spatial audio capabilities.
Table Comparison
Here’s a detailed comparison of the Marshall Stanmore III vs. Sonos Era 300 in table format:
| Specification | Marshall Stanmore III | Sonos Era 300 |
| Total Power Output | 80W total: 1 x 50W Class D amplifier for woofer, 2 x 15W Class D amplifiers for tweeters | Not officially specified, estimated over 100W total across six Class D amplifiers |
| Speaker Configuration | Two-way system: 1 x 5-inch woofer, 2 x 0.75-inch tweeters | Six-driver system: 4 tweeters (forward, side, and upward-firing), 2 woofers (left and right-facing) |
| Frequency Response | Estimated around 45 Hz – 20 kHz | Estimated range of 40 Hz – 20 kHz |
| Maximum SPL (Sound Pressure) | 97 dB @ 1 meter | Not officially listed, but capable of filling medium to large rooms |
| Connectivity | Bluetooth 5.2, 3.5mm AUX input, RCA input | Wi-Fi 6, Bluetooth 5.0, USB-C line-in (adapter required), Apple AirPlay 2 |
| Smart Integration | None | Voice control with Amazon Alexa and Sonos Voice Control |
| Multi-Room Capability | No native support | Yes, via Sonos ecosystem |
| Dolby Atmos / Spatial Audio | Not supported | Yes, supports spatial audio and Dolby Atmos via Wi-Fi playback |
| App Control | Marshall Bluetooth app (limited to EQ and pairing) | Full control via Sonos app including Trueplay room tuning and integration with streaming services |
| EQ Controls | Physical bass and treble knobs on top panel | Adjustable via Sonos app |
| Build Material | Vinyl-wrapped wooden cabinet, metal grille, brass-finished analog knobs | Plastic body with acoustic waveguide design for spatial dispersion |
| Dimensions (W x H x D) | 13.78 x 8.00 x 7.40 inches | 10.24 x 7.28 x 6.30 inches |
| Weight | 9.37 lbs (4.25 kg) | 9.85 lbs (4.47 kg) |
| Placement Orientation | Front-facing stereo setup | Multi-directional sound dispersion designed for room-filling 3D audio |
| Best Use Case | Small to medium rooms, casual music listening, vintage design lovers | Medium to large rooms, immersive modern audio, smart home or multi-room system users |
Sound Comparison
The Marshall Stanmore III and Sonos Era 300 gave me two very different listening experiences when I tested them with “Bad idea right?” by Olivia Rodrigo, “Lose Yourself to Dance” by Daft Punk, and Motion Picture Soundtrack by Radiohead. The Stanmore III, with its 80W output and two-way system, felt more direct and classic. In Olivia’s track, vocals were forward and slightly warm which made them feel personal and close. The 5-inch woofer held up well with the punchy low-end of the Daft Punk track, though it didn’t reach especially deep. It handled mid-bass confidently, and when I turned up the volume it kept its shape without sounding muddy. The two tweeters angled outward helped the stereo spread feel wider than I expected from a single-box setup, though it was still clearly front-facing.
The Era 300 was a different kind of experience. It uses six Class D amplifiers to drive four tweeters and two woofers in multiple directions, and it’s built to support spatial formats like Dolby Atmos. When I played Motion Picture Soundtrack, the difference was immediate. Sounds didn’t just come at me—they wrapped around the room. The side-firing and up-firing tweeters created this immersive dome of sound [especially noticeable with the harp and organ in that track]. It didn’t feel like one big speaker—it felt more like I was sitting in the middle of a performance. Lose Yourself to Dance had more low-end power compared to the Stanmore, with the bassline stretching wider and deeper into the room. Vocals sat a bit further back in the mix, not in a bad way but in a way that added to the feeling of space.
The two speakers almost feel like they’re trying to do different things. The Stanmore III gave me a clean and classic stereo sound that felt best for rock, vocal-heavy music, or anything where simplicity works in its favor. It was also easier to adjust on the fly using the analog knobs which I liked during long sessions. The Era 300 pushed boundaries more—it invited me to hear music in a different layout and with more dimension, especially with spatial mixes. Personally, I would go with the Era 300 because I think that sense of immersion is harder to get from other speakers, especially without adding extra equipment. The Stanmore III is still a joy to listen to and great for straightforward sessions, but the Era 300 feels more like the future of home listening.
Design Comparison
The Stanmore III features a classic, vintage-inspired look reminiscent of Marshall’s iconic guitar amplifiers and looks really classy in a home living room space. Its rectangular, boxy form is wrapped in textured vinyl, giving it a tactile and durable feel. The front panel is adorned with a woven grille cloth, prominently displaying the Marshall script logo, which adds to its nostalgic charm. On the top panel, brass-finished analog controls—including knobs for volume, bass, and treble—offer a hands-on, intuitive user experience. The inclusion of a toggle power switch further enhances its retro appeal. Measuring approximately 13.78 x 8.00 x 7.40 inches and weighing around 9.37 pounds, the Stanmore III has a substantial presence that feels robust and well-constructed. However, its design is decidedly traditional, which may appeal more to those with a penchant for vintage aesthetics.
In contrast, the Sonos Era 300 adopts a modern and unconventional design that reflects its forward-thinking approach to audio technology. The speaker’s unique hourglass shape is not merely for visual distinction but serves an acoustic purpose, facilitating the dispersion of sound to support spatial audio experiences. Its smooth, matte finish and seamless curves give it a contemporary, minimalist appearance that can blend into various interior styles. The top panel features a new user interface with a responsive volume slider and touch-sensitive controls for playback and voice assistance, emphasizing a sleek and modern user interaction. Measuring about 10.24 x 7.28 x 6.30 inches and weighing approximately 9.85 pounds, the Era 300 is slightly more compact than the Stanmore III but maintains a solid and sturdy build. Its design is geared towards delivering immersive, room-filling sound, aligning with its support for Dolby Atmos and spatial audio content.
The Verdict?
Overall. The Marshall Stanmore III is a really nice classy speaker to listen to with nice highs, midranges and good bass response. It delivers warm, solid stereo sound with 80W of power through a traditional two-way setup. I liked having the physical knobs for volume, bass, and treble—it made it easy to dial things in on the fly without opening an app. The build feels classic and solid, and the vintage amp look brings a kind of charm that fits right into a space with more character. It’s the kind of speaker I’d keep in a den or home office where I want reliable sound with a little personality.
The Era 300, though, is more a speaker designed for spacious immersive listening with 3D sound performance. Its six-driver array makes spatial audio really feel immersive, especially with Dolby Atmos tracks or anything with wide mixes. The curved, hourglass design actually plays into how the sound fills a room and the experience is less about pinpointing a left or right speaker and more about feeling like you’re inside the music. I think that makes a difference if you’re streaming modern content or using it in a living room.
Personally, I would go with the Era 300. I think that for the price and the space it takes up, it gives you a much more layered and spacious listening experience. The Stanmore III is still a strong speaker and I’d recommend it to anyone who loves its retro style or just wants a no-fuss setup. But overall, the Era 300 feels more complete for how I like to listen now.