MartinLogan is best known for its distinctive electrostatic loudspeakers, but the company has been expanding its home theater ambitions in 2026. Following the introduction of its Motion Discrete Cinema Series, featuring slim LCR speakers and passive soundbars, MartinLogan has unveiled the USR51, an ultra-slim 5.1-channel A/V receiver designed for custom installations where a conventional receiver would be about as welcome as a refrigerator mounted beneath the television.
If the design looks familiar, it’s because it’s an Anthem MRX SLM rebranded under the MartinLogan brand. All features are specifications are identical, highlighted by its small form factor, five channels of 50-watt Class D amplification, room correction capabilities, and compatibility with Dolby Vision, DTS:X and Dolby Atmos.
Ultimately, MartinLogan’s USR51 (just like Anthem MRX SLM) delivers genuine multichannel surround sound with separate loudspeakers and a powered subwoofer, without dedicating an entire cabinet to the electronics. Paired with MartinLogan’s new Discrete Cinema speakers, it offers an alternative to conventional powered soundbars for buyers who want their home theater heard rather than seen.
“In the AV world, almost every component has shrunk over the years,” says Allan Tarrant, Senior Vice President at MartinLogan. “From razor-thin displays to low-profile speakers, performance from compact designs is staggering. Yet despite these advances, most AV receivers have remained large and difficult to integrate into low-profile spaces. Our goal with the USR51 was to deliver a miniaturized, streamlined AVR that easily conceals behind the TV, solving the challenge of where to place equipment in space-saving installations. With the USR51, the answer can be as simple as ‘behind the TV.'”
Key Features
Ultra-Slim Stealth Profile: Significantly smaller than a conventional AV receiver, the MartinLogan USR51 delivers five channels of Class D amplification, rated at 50 watts per channel into 8 ohms or 92 watts per channel into 4 ohms (two channels driven). Its compact chassis can be mounted behind a television, inside a wall-mounted media box, or in shallow cabinetry where a full-size AVR would be impractical.
ARC Genesis Room Correction: The USR51 incorporates Anthem Room Correction (ARC Genesis), which uses a series of in-room measurements to compensate for acoustic problems caused by room dimensions, reflective surfaces, and speaker placement. The software runs on Mac and Windows computers and allows users to fine-tune bass and high-frequency response. Up to four speaker profiles can be stored for different listening positions, system configurations, or music and home theater applications. A calibrated USB microphone is included.
High-Resolution Streaming: Like many modern AV receivers, the USR51 supports music streaming through Apple AirPlay, Google Cast, Spotify Connect, and Bluetooth. This gives users several ways to listen without connecting a separate streamer. However, MartinLogan has not confirmed native TIDAL Connect or Qobuz Connect support at launch, and streaming resolution will depend on the service and connection method.
Physical Connectivity: The USR51 offers HDMI eARC, one HDMI input, optical digital audio, and a 3.5 mm analog input. HDMI eARC allows audio to return from a compatible television, while HDMI-CEC enables power and volume control using the TV’s existing remote. Optical and analog connections provide alternatives for sources without HDMI, although they don’t offer the same integrated control capabilities.
Smart Home Integration: Designed for custom installations, the USR51 supports IP and IR control, includes an IR remote, and works with the Anthem Remote App for iOS and Android. Integration with major home automation platforms is also supported, including Savant, Control4, URC, Crestron, RTI, Elan, AVA, and Josh.ai. This allows professional installers to incorporate the receiver into larger home control systems without requiring another remote on the coffee table.
Euroblock Speaker Connections: Instead of traditional binding posts, the USR51 uses a detachable 10-pin Euroblock connector, commonly referred to as a Phoenix-style terminal block. It accepts speaker wire up to 12 AWG (4 mm²), providing a compact alternative to conventional terminals. Connections are secured using a small flathead screwdriver, according to MartinLogan’s installation manual.
Flexible Mounting Options: The compact chassis can be placed on a shelf, mounted behind a television using the included VESA-compatible bracket, or installed on a wall or inside a structured in-wall media box. This allows installers to keep the electronics out of sight without requiring a conventional AV cabinet.
Shallow Cabinet Installation: The USR51 also fits into low-profile furniture and shallow cabinetry where traditional receivers would be impractical. The included external IR receiver or Anthem Remote App provides control when the unit is hidden from view, provided the installation maintains adequate ventilation.
Compact 1U Rack Mounting: For larger custom installations, the USR51 occupies just 1U of space in a standard 19-inch equipment rack when used with the optional rack-mounting kit, sold separately. This makes it suitable for centralized installations where rack space is limited.
WebUI & App Control: Designed without an on-screen display, it prevents viewer disruption. Detailed configurations are managed via the intuitive WebUI or Control App, with volume status displaying naturally on screen.
“The growing popularity of low-profile speaker systems has driven the need for more compact, streamlined amplification,” says Andrew Lindsey, Product Manager at MartinLogan. “The USR51 eliminates the need for deep furniture or remote gear mounting when adding a surround system. Simply mounting a USR51 and a media streaming device behind a TV fulfills most listeners’ needs. Complex systems that aren’t easy to use can be a point of contention for end users, but USR51 resolves this by offering compatibility with leading control platforms and leveraging the simplicity of eARC. Given the compact design of USR51, there is no space for a bunch of HDMI inputs, so eARC enables a simple yet high-performance audio experience in an ultra-slim chassis that allows you to add multi-channel audio almost anywhere.”
The USR51 is designed to complement MartinLogan’s Motion SLM Series, Motion Compact Series (2i, 4i, 6i, and 8i), Motion Discrete Cinema Series, and its extensive lineup of architectural loudspeakers. Together, they offer a discreet home theater solution for installations where homeowners want genuine multichannel sound without visible electronics or bulky loudspeakers dominating the room.
MartinLogan USR51 Specifications
| MartinLogan Model | USR51 |
| Product Type | Slim AVR |
| Price | $1,299.99 |
| Amplifier Type | Class D |
| Number of Amplified Channels | 5 |
| Subwoofer Output | Yes – 1 |
| Speaker Output (0 DBFS Digital Input, 1 W Output into 8 ohms) | Frequency Response 20 Hz – 20 kHz (+/-0.5dB) S/N Ratio (IEC-A filter) 92 dB THD+N ratio (1 kHz, 20-22 kHz filter) -87 dB |
| Speaker Output (1 VRMS Analog Input, 1 W Output in 8 ohms) | Frequency Response 20 Hz – 20 kHz (+/-0.5dB) S/N Ratio (IEC-A filter) 88 dB THD+N ratio (1 kHz, 20-22 kHz filter) -85 dB |
| Speaker Impedance | Compatible with 4 Ohms or higher impedance. |
| FTC Power Output Rating (1% THD) | Channels 1-5, Two Driven into 8 Ohms 50 W Channels 1-5, Two Driven into 4 Ohms 92 W |
| Surround Sound and Audio Format Support | Dolby Atmos, DTS:X, Stereo, All-Channel Stereo, Mono, and All-Channel Mono |
| HDR Support | Dolby Vision |
| Room Correction | ARC Genesis |
| External Control | Crestron, Control4, SAVANT, URC, ELAN, RTI, AVA, Josh.ai |
| Control App | Anthem Remote App (iOS/Android) |
| IR Remote | Yes |
| Bluetooth | Yes |
| Apple AirPlay | Yes |
| Google Cast | Yes |
| Spotify Connect | Yes |
| HDMI | 1-In / 1-Out (eARC) |
| Digital Optical | 1-In |
| Analog | 1-In |
| USB | 1 – Update Only |
| Ethernet (LAN – 10/100) | 1 |
| Speaker Connections | Toolless Phoenix Terminals |
| IR Externer | 1-in |
| Power Consumption – Typical Load (1/8th power, all channels driven into 8 ohms) | < 50 W |
| Power Consumption – Standby (IP Control Enabled) | < 2 W |
| Power Consumption – Standby (IP Control + HDMI Bypass Enabled) | < 5 W |
| Power Requirements | 120V – 220/240V |
| Dimensions – Height | (without feet) 1.5″ / 3.8 cm (with feet) 1.7″ / 3.8 cm (with rackmount kit) 1U / 1.75″ / 4.4 cm |
| Dimensions – Width | 11″ / 27.9 cm (with rackmount Kit) 19″ / 43.2 cm |
| Dimensions – Depth | 11″ / 27.9 cm (including power cord 13″ / 33.0 cm |
| Weight | 6.6 lb / 3.0 kg |
The Competition
Other than the identical Anthem MRX SLM, there currently aren’t any A/V receivers of the same size or smaller. Marantz has released slimline AVRs including the NR1510, Cinema 70s, and Cinema 70s Series 2. However, they’re essentially half-height home theater receivers, which do offer more connectivity and features.
For those who want TV connectivity in a small form factor, Naim CI-Uniti 102 deserves consideration for stereo-only applications. At $1,499, Naim offers 150 watts per channel into 8 ohms, HDMI eARC, an extensive streaming platform, DSP controls, and multi-room integration. It also sounds considerably more convincing than its anonymous black chassis suggests.
The distinction is that Naim is primarily a two-channel streaming amplifier, with support for a subwoofer, whereas MartinLogan provides five powered channels and surround decoding. For stereo listening and larger power demands, the Naim is particularly attractive. For a discreet 5.1-channel home theater, the USR51 is the more appropriate choice.
The Bottom Line
MartinLogan’s USR51 is essentially the Anthem MRX SLM with a different logo, sharing its core architecture, amplification specifications, ARC Genesis room correction, and installation flexibility. That’s hardly a criticism. We reviewed the Anthem MRX SLM and came away impressed by its performance, straightforward operation, and ability to deliver genuine 5.1-channel surround sound without requiring a conventional equipment rack.
What makes the USR51 interesting isn’t revolutionary new technology, but how MartinLogan has positioned it within its growing custom-installation ecosystem. Paired with the company’s Motion SLM, Discrete Cinema, or architectural loudspeakers, it offers a practical alternative to powered soundbars for homeowners who want separate speakers, proper surround sound, and electronics that disappear behind the television. ARC Genesis is a significant advantage, particularly in rooms where speaker placement is dictated more by interior design than ideal acoustics.
There are compromises. The amplifier is rated at 50 watts per channel into 8 ohms or 92 watts into 4 ohms, both with two channels driven. That’s adequate for many smaller rooms and reasonably efficient loudspeakers, but demanding speakers and larger spaces may require more muscle. There’s also only one HDMI input, so multiple video sources are generally better connected directly to the television, with audio returned through eARC. If the TV runs out of inputs, an external HDMI switch may be necessary. There’s no dedicated phono stage, no height-channel amplification for a Dolby Atmos speaker system, and no AM/FM tuner. Calling it an AVR might offend a few traditionalists, although I suspect most installers have more pressing concerns than finding a local FM station.
At $1,299.99, the USR51 makes the most sense for homeowners and custom installers who prioritize clean installations, room correction, and genuine surround sound over maximum connectivity and expansion. It doesn’t offer a compelling technical reason for existing Anthem MRX SLM owners to replace their receivers, but it gives MartinLogan dealers a logical centerpiece for the company’s growing family of low-profile loudspeakers.
Pricing & Availability
- MartinLogan USR51 – $1,299.99 at authorized MartinLogan dealers and integrators
- Anthem MRX SLM – $1,299.99 at Crutchfield and Audio Advice
For more information: martinlogan.com
Related Reading:
- Best A/V Receivers: Editors’ Choice
- MartinLogan Depth Series Subwoofers Plunge Into the Lower Depths — Down to a Bone-Rattling 18Hz
- MartinLogan Grotto 12 & 15 Subwoofers Deliver High-Output 2kW Hybrid Bass Performance For Your Home Theater
- MartinLogan Motion Foundation B1 Bookshelf Speaker Review: There’s More Air There
