Russound D250LS

Russound D250LS, the local source amplifier

In a multi-room sound system, all zones receive the same centralized source. There remains the case of the bedroom or office, where you may sometimes want to listen to the room’s television or computer rather than the general broadcast. The D250LS from Russound addresses exactly this need: a compact stereo amplifier that switches the zone’s speakers to the local source as soon as it starts, then returns them to the central sound system once that source is turned off.

When the local source takes control

The LS suffix in the name refers to this “local source” function. The principle is straightforward. As long as nothing is playing locally, the room’s speakers play the multi-room system source. Turn on the television or computer connected to the D250LS, and the D250LS detects the signal, disconnects the central system and sends its own amplification to the speakers. When the local source stops, the speakers return to the general broadcast.

Several detection methods are provided depending on the type of source. Signal detection works with line-level inputs (low voltage, typically an RCA output) as well as speaker-level inputs (the already amplified signal from a small television, for example). Video signal detection and a 12 V trigger input complete the package for installations that control switching through other equipment. An adjustable switching delay, from five seconds to five minutes, prevents the speakers from switching at every brief sound or from returning too quickly to the central source.

Two-channel stereo or mono bridge

In stereo operation, the D250LS delivers 50 watts per channel into 8 ohms and 75 watts per channel into 4 ohms, the minimum impedance allowed in this mode. A stereo / mono bridge selector combines the two channels into a single 150-watt output into 8 ohms, useful for powering a speaker requiring more headroom or a single listening point. The eight screw terminals accept up to four speakers.

This is Class D amplification, which explains its low heat output and light 2.1 kg weight. Each channel includes thermal protection and short-circuit protection, which shut off the output in the event of prolonged overheating or a faulty speaker cable. In terms of measurements, THD+N distortion remains below 0.3% from 20 Hz to 20 kHz at 50 watts into 8 ohms, and drops below 0.05% at 1 watt. The A-weighted signal-to-noise ratio exceeds 112 dB, frequency response stays within ± 0.4 dB from 20 Hz to 20 kHz, and gain reaches 32 dB with a 47 kilohm line-level input impedance.

Four installation options

The flat chassis, 4.45 cm high (equivalent to a 1U rack), fits where a conventional amplifier would not. The supplied hardware enables four mounting options: flat on a shelf, wall-mounted, installed alone in a 1U space, or side by side with a second D250LS in that same 1U space to cover two zones within the height of a single rack. The unit measures 21.6 cm wide by 26.7 cm deep and weighs 2.1 kg.

Power is supplied via a detachable IEC mains cable, on the European 230 V model. Standby power consumption remains below 0.5 watt, in compliance with European requirements in this area. A 12 V trigger input and output allow switching to be daisy-chained with a multi-room controller or other components in the installation.

Frequently asked questions

Does the D250LS work without a multi-room system, as a simple zone amplifier?

Yes. Without a local source to monitor, it serves as a stereo amplifier for a zone: two channels, 50 watts per channel into 8 ohms, with the same line-level inputs. The switching function then remains inactive.

Can two pairs of speakers be connected?

The eight terminals accept up to four speakers, with the outputs wired in parallel on each channel. Be mindful of the resulting impedance: two 8-ohm speakers in parallel present 4 ohms, which is the minimum allowed in stereo. Below that, the protection may trip.

What can mono bridge mode power?

The two combined channels deliver 150 watts into a single 8-ohm load, enough to power a demanding speaker or a single listening point. The D250LS does not include any dedicated filtering for a subwoofer: without bass filtered upstream, it is not intended for this role.

Is a Russound controller required?

No. The D250LS can be used on its own, as a zone amplifier or for local source switching. The 12 V trigger inputs and outputs are used to integrate it with a multi-room controller or daisy-chain several components when the installation requires it.

Is the D250LS suitable for French mains power?

Yes, in its European version powered by 230 V / 50 Hz, with a detachable IEC mains cable and T3.15AL fuse. Standby consumption remains below 0.5 watt.

How does the D250LS differ from Russound’s MBX-AMP amplifier?

The MBX-AMP is a connected amplifier that plays network sources itself (AirPlay, Chromecast, Bluetooth, streaming services). The D250LS has no network playback capability: it is a power amplifier that receives the signal from an existing source and manages switching between that local source and the central sound system. The two meet different needs in a multi-room installation.

Does the D250LS need ventilation?

Its Class D amplification generates little heat, but each channel still has thermal protection. Airflow space around the chassis is recommended, especially if it is operated loudly for extended periods or installed in an enclosed space.

Technical Specifications

Overview

• Two-channel stereo amplifier with priority local source
• Compact, low-profile form factor
• Automatic local source switching
• Bridgeable channels for high-power mono output
• Thermal and short-circuit protection on each output channel

Output Power

• Continuous output power (< 0.3% THD+N at 1 kHz)
  • 50 W per channel into 8 ohms
  • 75 W per channel into 4 ohms
  • 150 W into 8 ohms in bridged mode (2 channels)
• Stereo / bridged mono switch to combine both channels

Audio Performance

• Distortion (THD+N)
  • < 0.3% from 20 Hz to 20 kHz at 50 W into 8 ohms
  • < 0.05% from 20 Hz to 20 kHz at 1 W into 8 ohms
• Signal-to-noise ratio: > 112 dB A-weighted
• Channel separation: > 60 dB at 1 kHz
• Frequency response: 20 Hz to 20 kHz ± 0.4 dB
• Voltage gain: 32 dB

Inputs and Sensitivity

• Input sensitivity
  • 70 mV for 1 W into 8 ohms
  • 550 mV for 50 W into 8 ohms
• Input impedance: 47 kohms on line input
• Automatic signal detection for high- and low-level inputs, video signal, and 12 V trigger

Switching and Triggering

• Adjustable switching delay: 5 seconds to 5 minutes
• Trigger input: 12 V DC, 10 kohms
• Trigger output: 12 V DC, 100 mA maximum

Power Supply

• Automatic switching power supply
  • North American model: 120 V AC, 60 Hz, 2.5 A
  • European model: 230 V AC, 50 Hz, 2.5 A
• IEC 320 connector with detachable 3-prong power cord
• Fuse rating: T3.15AL / 250 V
• Standby power consumption: < 0.5 W

Installation

• Four mounting options
  • Wall mounting
  • Shelf placement
  • 1U rack mounting
  • Side-by-side mounting of two amplifiers in a 1U rack
• Compatible with the MCA-C5 controller for powering zones 7 and 8
• Mounting hardware included

Dimensions and Weight

• Dimensions: 21.59 cm (W) x 26.67 cm (D) x 4.45 cm (H)
• Weight: 2.1 kg