KEF Kube 8 MIE 8 Inch 300W RMS Powered Subwoofer

Compact Sealed Bass for Smaller Rooms

The KEF Kube 8 MIE is a compact powered subwoofer designed for smaller rooms, apartments, bedrooms, offices, gaming spaces, music systems, and space-conscious home theaters. Its sealed cabinet and front-firing 8" driver make it easier to place than a larger subwoofer while still adding meaningful low-frequency extension and impact.

The Kube 8 MIE combines a long-throw 8" driver, 300W RMS Class D amplifier, and KEF's Music Integrity Engine DSP to help maintain controlled bass across different listening levels and room positions.

Key Specifications

• Sold as: One powered subwoofer
• Design: Sealed, front-firing
• Driver: 1 × 200 mm (8") long-throw driver
• Amplifier: Built-in Class D
• Amplifier power: 300W RMS
• Frequency response: 34 Hz–140 Hz (-6 dB)
• Maximum output: 105 dB
• Variable low-pass filter: 40–140 Hz, plus LFE mode
• Inputs: RCA phono, speaker-level input, KW1 expansion port
• Power: 100–240V AC, 50/60 Hz

Who Should Choose the Kube 8 MIE?

Choose the Kube 8 MIE when you want a compact powered subwoofer that is easier to place than larger models. KEF specifically positions it for smaller rooms, making it a strong choice for bedrooms, apartments, offices, compact living rooms, gaming setups, and smaller stereo or home theater systems.

If your room is larger or you listen at higher levels, a larger Kube model may provide deeper extension and more output.

300W RMS Built-In Amplification

The Kube 8 MIE includes a 300W RMS Class D amplifier, so no separate power amplifier is required. Connect the subwoofer to your system, plug it into AC power, and configure its level, crossover, and placement settings.

KEF explicitly publishes the 300W figure as an RMS amplifier-output rating.

Music Integrity Engine and iBX

KEF's Music Integrity Engine uses proprietary DSP algorithms to coordinate the driver, amplifier, and cabinet. iBX Intelligent Bass Extension dynamically adjusts low-frequency behavior to help maintain bass depth and control across different listening levels.

34 Hz–140 Hz Response

KEF specifies a frequency response of 34 Hz–140 Hz at -6 dB and a maximum output of 105 dB measured at 1 meter.

The Kube 8 MIE is designed to add low-frequency support rather than reproduce the extreme infrasonic extension of KEF's higher-end subwoofers. Its strength is combining useful bass extension with a compact cabinet.

Flexible Wired Connectivity

The Kube 8 MIE provides RCA line-level inputs for AV receivers, processors, preamps, and integrated amplifiers with compatible outputs.

It also includes speaker-level inputs, allowing integration with systems that do not provide a dedicated subwoofer pre-out.

KEF SmartConnect

KEF SmartConnect automatically detects whether a mono or stereo RCA input is being used and adjusts gain accordingly, simplifying integration without requiring a Y-adapter for a single RCA connection.

Optional KW1 Wireless Connection

The Kube 8 MIE does not include built-in wireless audio. Wireless subwoofer operation requires the optional KEF KW1 Wireless Subwoofer Adapter Kit, connected through the dedicated expansion port.

The subwoofer still requires AC power when the KW1 is used.

Three Room Placement EQ Presets

The Kube 8 MIE includes three placement-dependent EQ settings to help compensate for different room positions:

• Room: For more open placement
• Wall/Cabinet: For placement near a wall or inside appropriate cabinetry
• Corner: For corner placement where boundary reinforcement is strongest

These settings help reduce excessive bass buildup caused by nearby walls and corners.

Power-On Modes

The Kube 8 MIE supports multiple power modes, including signal-sensing auto wake, Always On mode, and 12V trigger control for compatible systems.

Placement Flexibility

Because the Kube 8 MIE is front-firing, KEF allows placement near walls, in corners, and even in suitable cabinets. Bass response can vary significantly by position, so testing several locations is still recommended.

Dimensions and Weight

• Height: 293 mm (11.5")
• Width: 293 mm (11.5")
• Depth: 310 mm (12.2") including rear panel and feet
• Weight: 9.4 kg (20.7 lb)

What's Included?

• 1 KEF Kube 8 MIE powered subwoofer
• Power cord
• Euroblock speaker-level connector
• User manual and warranty information

The optional KEF KW1 wireless adapter, RCA/LFE cable, and other system cables are sold separately.

Complete Your Audio System

• Subwoofers
• AV Receivers & Surround Sound
• KEF Speakers & Audio

Need Help Choosing the Right Subwoofer?

Send Bear Security Shop your room dimensions, speakers, amplifier or AV receiver model, and listening goals. We can help compare the Kube 8 MIE with larger Kube models and recommend the best connection and placement approach for your system.

Is the KEF Kube 8 MIE powered?

Yes. It includes a built-in 300W RMS Class D amplifier.

What size driver does it use?

The Kube 8 MIE uses one front-firing 8" long-throw driver.

What is the frequency response?

KEF specifies 34 Hz–140 Hz at -6 dB.

What is the maximum output?

KEF specifies a maximum output of 105 dB measured at 1 meter.

What crossover range does it support?

The variable low-pass filter operates from 40 Hz to 140 Hz, plus an LFE mode for AV receiver and processor integration.

Can I connect it to an AV receiver?

Yes. The Kube 8 MIE includes RCA inputs for connection to compatible subwoofer or LFE outputs.

Can I use it with an amplifier that has no subwoofer output?

Yes. It includes speaker-level inputs for integration with compatible amplifiers and receivers.

Does it have built-in wireless audio?

No. Wireless operation requires the optional KEF KW1 Wireless Subwoofer Adapter Kit. The subwoofer still requires AC power.

What does KEF SmartConnect do?

SmartConnect detects whether a mono or stereo RCA input is connected and automatically adjusts gain for the connection method.

What placement EQ settings are available?

The Kube 8 MIE provides three placement EQ presets for room, wall/cabinet, and corner positioning.

Can I place it near a wall or in a cabinet?

Yes. KEF specifically allows placement near walls, in corners, and in suitable cabinets. Use the placement EQ and test different positions for the smoothest bass response.

Does it support automatic power-on?

Yes. It supports signal-sensing auto wake, Always On mode, and 12V trigger control.

What are the dimensions?

The Kube 8 MIE measures approximately 11.5" H × 11.5" W × 12.2" D including the rear panel and feet.

How much does it weigh?

KEF specifies a weight of 9.4 kg, approximately 20.7 lb.

What comes in the box?

KEF includes the Kube 8 MIE subwoofer, power cord, Euroblock speaker-level connector, and user manual/warranty information.