iFi SilentPower DC Blocker

SilentPower DC Blocker is a compact, plug-in solution for eliminating mechanical transformer hum caused by DC offset on your AC mains. Designed to sit directly at your component’s IEC power inlet, it blocks incoming DC (up to 1,200mV) before it can saturate a toroidal transformer—helping your amplifier or source gear run quieter and more consistently. Unlike many “fixes,” it’s built to retain EMI shielding at the power source and is engineered with safety-focused materials and components for confident everyday use. If you’ve got a big amp with an annoying chassis buzz, this is the simple add-on that targets the root cause without changing how you power your system.

What It's Good At:

• Eliminating audible mechanical hum from toroidal transformers caused by DC on the mains
• Preserving EMI shielding while stopping DC offset at the IEC inlet
• Supporting global systems with a wide 90–240V voltage rating
• Handling demanding setups with >7A maximum current rating and 4A continuous rating
• Fitting neatly behind gear thanks to its small, universal-application form factor
• Adding peace of mind with fire-resistant, safety-minded construction and robust electrical specs

iFi DC Blocker Full Specifications:

• Product name: DC Blocker
• Brand/Store: SilentPower
• SKU: 03-06-041-0001-00
• Technology: ZERO DC Block technology
• DC blocking capability: Blocks incoming DC up to 1,200mV (1.2V)
• DC pass-through: 0 DC pass through (per product feature description)
• Voltage rating: 90–240V
• Maximum current rating: > 7A
• Continuous current rating: 4A
• Max amplifier power: 880W or VA on 220V; 440W or VA on 110V
• Connector type: Universal IEC
• Connector grade: Hospital-grade IEC connectors
• Construction/safety notes:
  • High-performance glass passivated semiconductor
  • High-case dielectric strength: 1500VRMS
  • UL listed (as stated in product feature description)
  • Flame resistant IEC socket/connector/chassis
  • Fireproof polymers: UL94-V0
• EMI shielding: Retained
• Dimensions: 68 × 37 × 32 mm / 2.7” × 1.5” × 1.3”
• Weight: 63g / 2.2oz
• In the box: 1× DC-blocker, 1× User Manual
• Note: The image colour may differ from the actual product due to lighting. Please refer to the product for accuracy.
• Compatibility guidance (from FAQ): Mainly designed for source equipment and amplifiers with a power transformer rating up to 500W (for 230V) or 350W (for 115V). Using equipment with a higher power rating is ok though; DC blocking will still work, but to a lesser degree.

iFi DC Blocker Q&A:

How can I tell if I need a DC blocker?

If your powered audio gear has an audible mechanical hum (especially gear using a toroidal transformer), a DC blocker is designed to reduce or remove that noise by stopping DC offset from reaching the transformer.

How do I install and use the DC Blocker?

Insert the DC Blocker into your component’s IEC mains input, then plug your power cord into the DC Blocker. It’s placed at the rear power inlet of the equipment.

Can I use the DC Blocker on more than one component?

Yes. You can use a DC Blocker on each piece of equipment that has a power transformer in its power supply.

What is it doing electrically to reduce the hum?

It reduces hum by blocking DC from entering the transformer’s primary side, helping prevent transformer saturation.

Is the DC Blocker safe to use?

Yes. It’s designed to be safe and uses fire-resistant construction (described as a fireproof product).

Do I need one DC Blocker or multiple for my system?

You typically need one DC Blocker per power bar/conditioner.

Will it work with high-power amplifiers or only smaller components?

It’s mainly designed for source gear and amplifiers up to 500W (230V) or 350W (115V) transformer ratings, but higher-power equipment can still be used. DC blocking will still function, though typically to a lesser degree.

Will it negatively affect my audio performance?

It’s designed not to negatively affect connected audio products, and it may improve perceived sound quality by removing excess DC voltage.

iFi DC Blocker Downloads:

iFi SilentPower DC Blocker Connection Guide