Supra MainBlock MD04-EU/SP Switch

The LoRad range, which includes this MD04-EU/SP Switch power strip, combines radio frequency interference filtering, surge protection, and electromagnetic shielding. All of this comes in a compact enclosure that blends discreetly into an audio or home cinema system, without the sonic compromises often associated with traditional mains filters.

An aluminum chassis dedicated to shielding

The body of the MD04-EU/SP is machined from an aluminum extrusion that forms a Faraday cage around the internal components. This conductive shell intercepts unwanted electric fields emitted by nearby equipment (cordless DECT phones, Wi-Fi routers, dimmer switches, electric motors) and routes them to ground. The chassis measures 325 mm in length, 90 mm in width, and 50 mm in height, allowing it to be tucked under furniture or mounted on a wall using the dedicated mounting points. The unit weighs one kilogram, a sign of robust construction.

For the shielding to work optimally, the strip must be connected to a wall outlet with a functional earth connection. Pairing it with a shielded mains cable from the Supra LoRad range extends the protection right up to the wall outlet and maximizes the overall benefit.

NIF filtering: reducing noise without constraining dynamics

The NIF (Non-Intrusive Filtering) circuit in this power strip was developed in partnership with the British laboratory Ben Duncan Research. Its design is based on selective attenuation of high-frequency interference (RFI), which can exceed 40 dB, while preserving the 50 Hz mains sine wave intact. In practice, noise generated by domestic appliances is reduced without affecting the transient behavior of the connected power supplies.

Three of the four Schuko outlets feature this NIF filtering, while the first outlet (the one nearest the IEC inlet) remains unfiltered. This configuration allows you to plug a power amplifier into the direct output, where current demands can be high, and reserve the filtered outlets for digital sources, preamplifiers, or other less power-hungry devices.

Surge protection

Unlike basic surge protectors that only safeguard the line-to-neutral path, the SP (Surge Protection) device integrated into the MD04-EU/SP acts on three distinct paths: line to neutral, line to earth, and neutral to earth. This three-way architecture intercepts both transient overvoltages carried by the grid and disturbances induced by a nearby lightning strike, which generally propagate towards earth.

Trigger thresholds are calibrated at 2.5 kV between line and neutral, and 4 kV between line or neutral and earth (Uc value). The residual protection voltage (Up) reaches 2 kV to 2.05 kV depending on the mode in question, which corresponds to a Type 3 classification. This level of protection is intended for sensitive equipment located at the end of the line, downstream from any main surge arrester installed at the electrical panel.

Switch and internal wiring

The bipolar On/Off switch, of the “high in-rush” type, withstands the high inrush currents encountered when powering up amplifiers or capacitor-based power supplies. Its switching capacity reaches 16 A in transient mode. In the Off position, it completely cuts power to all connected devices, eliminating any residual standby consumption.

The internal wiring uses tinned OFC (Oxygen-Free Copper) conductors with a cross-section of 2.5 mm², sufficient to deliver up to 2,500 W continuously at 250 V and 10 A. A time-delay ceramic fuse (10 A) protects the unit against overcurrent. The mains inlet uses a male IEC C14 connector (standard 10 A), compatible with most detachable power cords on the market.

Schuko outlets and correct polarity

The four outputs use the Schuko (CEE 7/4) format, a widely used standard in continental Europe. This standard has the advantage of placing the earth contacts on the sides of the plug, allowing you to rotate it 180° to optimize phase alignment of the devices. By trying both orientations, it is often possible to reduce the residual background noise of an audio system.

The internal outlets are Supra MCH-16/EU models, designed for optimal contact and enhanced durability. Final assembly is carried out at the Supra factory in Ljungskile, Sweden, using components manufactured in Germany and Sweden.

Integration into a system

The MD04-EU/SP Switch is equally suitable for a compact stereo system or a medium-sized home cinema setup. Four outlets allow, for example, connection of a power amplifier (to the unfiltered output), a network player, a DAC, and a preamplifier or AV processor. For larger systems, Supra offers six-, eight- or ten-outlet models, with or without a switch.

Since the mains cable is not supplied, you will need a cord fitted with a female IEC C13 or C15 connector on the strip side. The manufacturer recommends cables from its LoRad 2.5 range, whose shielding effectively complements that of the chassis.

Technical specifications

Protection and filtering

• Shielded aluminum chassis
  • Protection against electromagnetic interference (Wi‑Fi, telephones, dimmers, etc.)
• Non-intrusive NIF filtering
  • Up to 40 dB RFI attenuation
  • No dynamic range compression
• Type 3 surge protection
  • Phase to Neutral: Uc 2.5 kV, Up 2.0–2.05 kV
  • Phase to Earth: Uc 4.0 kV, Up 2.0–2.05 kV
  • Neutral to Earth: Uc 4.0 kV, Up 2.0–2.05 kV
  • Protection against mains surges and indirect lightning

Electrical specifications

• Rated voltage: 250 V
• Rated current: 10 A
• Maximum power: 2500 W
• Fuse: 10 A time-delay ceramic (Slow)
• Internal wiring: Tinned OFC copper 2.5 mm²
  • Stable, powerful energy transfer

Sockets and connectivity

• Total number of outlets: 4
  • 1 unfiltered outlet (ideal for amplifiers)
  • 3 NIF filtered outlets
• Output socket type: Schuko SUPRA MCH-16/EU (16 A)
• Mains input: SUPRA MCH-10, IEC C14 (10 A)
• High-capacity on / off switch
  • Complete power shutoff
  • No standby consumption

Construction and finish

• Product type: Filtered mains block
• Regional standard: European
• Shielding: Aluminum chassis
• Color: Aluminum
• Performance rating: Better

Dimensions and weight

• Dimensions (W × D × H): 325 × 90 × 50 mm
• Weight: 1 kg