O-NOORUS D4 PRO

TPA3255 PFFB Integrated Hi-Fi Amplifier with HDMI eARC, Balanced Input & Advanced 2.1 Crossover

The O-NOORUS D4 PRO is a highly versatile integrated Class-D Hi-Fi amplifier designed for listeners who want serious amplification, extensive connectivity, and advanced speaker/subwoofer integration in a compact chassis.

Built around the renowned Texas Instruments TPA3255 amplifier platform with Post-Filter Feedback (PFFB) technology, the D4 PRO combines powerful stereo amplification with HDMI eARC/ARC, USB, optical, coaxial, Bluetooth, RCA and balanced inputs.

But what truly sets the D4 PRO apart is its advanced system control. With independent High-Pass Filter (HPF) for the main speakers and Low-Pass Filter (LPF) for the subwoofer, it can form the heart of a properly integrated 2.1 system without requiring a separate crossover or DSP.

Add a hardware-controlled 3-band Bass/Mid/Treble EQ with a dedicated bypass mode, and the D4 PRO becomes an exceptionally flexible amplifier for Hi-Fi, desktop audio, TV systems and compact home theater setups.

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A More Complete Evolution of the D4 Series

The D4 PRO takes the core concept of the D4 and D4 II further by adding features normally found on considerably more expensive integrated amplifiers.

Key upgrades include:

• Balanced audio input
• HDMI eARC/ARC with CEC
• Independent HPF for main speakers
• Independent LPF for subwoofer
• 60Hz / 80Hz / 120Hz crossover selection
• 4th-order Butterworth HPF
• 3-band Bass, Mid & Treble control
• Dedicated Tone Bypass mode
• USB, Optical & Coaxial digital inputs
• Bluetooth connectivity
• RCA analog input
• Up to 200W per channel
• TPA3255 with PFFB architecture

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Powerful TPA3255 PFFB Amplification

At the heart of the D4 PRO is the TPA3255, one of Texas Instruments’ most capable high-performance Class-D amplifier platforms.

Combined with Post-Filter Feedback (PFFB) technology, the amplifier is designed to achieve excellent linearity, low distortion and strong control over the connected speakers.

With up to 200W per channel, the D4 PRO has the power required to drive a wide range of bookshelf, stand-mount and floorstanding speakers.

Whether you’re listening at moderate levels or want the system to open up during demanding musical passages, the D4 PRO provides substantial power in a compact form.

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Advanced 2.1 Crossover Management

One of the biggest advantages of the D4 PRO is its built-in active crossover system.

Instead of simply sending the full-range signal to both your speakers and subwoofer, the D4 PRO can divide the frequency spectrum between them.

Main Speaker High-Pass Filter

The main speaker output offers:

• 60Hz
• 80Hz
• 120Hz
• Bypass

The HPF uses a 4th-order Butterworth filter, allowing the main speakers to focus on the frequencies they are best suited to reproduce.

This can reduce low-frequency workload on smaller bookshelf speakers, helping improve clarity, dynamics and overall system performance.

Subwoofer Low-Pass Filter

The dedicated subwoofer output provides a matching:

• 60Hz
• 80Hz
• 120Hz
• Bypass

LPF selection.

This allows the subwoofer to concentrate on deep bass while the main speakers handle the midrange and treble.

Build a Proper 2.1 System

Connect a pair of quality bookshelf speakers and an active subwoofer, select the appropriate crossover point, and the D4 PRO becomes a complete 2.1 control center.

For smaller bookshelf speakers, an 80Hz or 120Hz crossover can be particularly useful. Larger speakers may benefit from a lower crossover such as 60Hz.

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HDMI eARC/ARC for Modern TV Systems

The D4 PRO is designed to work just as easily with a modern television as it does with traditional Hi-Fi sources.

Connect your TV through HDMI eARC/ARC and enjoy high-quality stereo audio through your speakers.

With CEC support, compatible TVs can synchronize power and volume control with the amplifier.

That means you can use your regular TV remote to control the system without needing a separate amplifier remote for everyday TV listening.

Perfect for:

• Smart TVs
• Netflix & streaming services
• YouTube
• Gaming
• Movies
• TV broadcasts
• Music playback from your television

It is an easy way to transform a TV into a significantly more capable stereo or 2.1 audio system.

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Balanced Input for Cleaner Connectivity

The D4 PRO adds a balanced audio input, making it a particularly interesting choice for users with balanced DACs, streamers and other high-quality source components.

Balanced connections can provide better resistance to noise and interference, particularly when source and amplifier components are separated by longer cable runs.

For users building a more serious Hi-Fi system, this is an important upgrade over the connectivity offered by many compact integrated amplifiers.

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3-Band Hardware Tone Control

Not every room or speaker sounds exactly the same—and sometimes you simply want to tailor the sound to your preference.

The D4 PRO provides independent:

Bass

Adjust low-frequency energy to suit your speakers, room and listening preference.

Mid

Fine-tune the important vocal and instrumental region.

Treble

Adjust high-frequency presence and overall brightness.

The tone controls provide up to ±12dB adjustment.

And when you want the cleanest possible signal path, simply activate Tone Bypass to completely bypass the tone-control circuitry.

So you can choose between:

Precise sound customization
or
Direct, unaltered playback

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Extensive Connectivity

The D4 PRO can accommodate virtually every common digital and analog source in a modern Hi-Fi system.

Digital Inputs

USB
Connect a computer or compatible digital source directly to the amplifier.

Optical
Ideal for TVs, CD players, streamers and other digital sources.

Coaxial
Connect digital transports, CD players and other digital audio equipment.

The optical and coaxial inputs support up to 24-bit / 192kHz digital audio.

HDMI eARC/ARC

Connect your television with a single HDMI cable and take advantage of CEC control.

Bluetooth

Wirelessly stream music from smartphones, tablets and other compatible Bluetooth devices.

RCA

For traditional analog sources such as DACs, CD players, streamers and other line-level equipment.

Balanced Input

For compatible balanced source components and higher-performance Hi-Fi setups.

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One Amplifier. Multiple Systems.

The versatility of the D4 PRO makes it suitable for a wide range of applications.

Hi-Fi Stereo

Pair it with a quality bookshelf or floorstanding speaker and a digital source for a compact high-performance music system.

2.1 Music System

Add an active subwoofer and use the built-in HPF/LPF crossover to create a properly integrated 2.1 setup.

TV Audio System

Connect your TV through HDMI eARC/ARC and enjoy significantly more powerful and refined stereo sound.

Desktop Hi-Fi

Connect a computer through USB, add compact bookshelf speakers and a subwoofer, and create a powerful desktop audio system.

Compact Home Theater

HDMI eARC/ARC, powerful stereo amplification and dedicated subwoofer management make the D4 PRO an excellent solution for compact two-channel home theater systems.

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Designed for the Modern Audiophile

The D4 PRO bridges the gap between traditional Hi-Fi and modern digital entertainment.

You can connect:

TV → HDMI eARC
PC → USB
CD Transport → Optical/Coaxial
Streamer/DAC → Balanced/RCA
Phone → Bluetooth
Active Subwoofer → Dedicated Subwoofer Output

All from one compact integrated amplifier.

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Why Choose the D4 PRO?

If you simply need a powerful Class-D amplifier, there are many options available.

The D4 PRO is different because it combines power, connectivity and system-level control in one unit.

The highlights:

TPA3255 + PFFB
Powerful, efficient and high-performance Class-D amplification.

HDMI eARC/ARC + CEC
Modern TV connectivity with convenient remote control.

Balanced Input
A higher-level connection option for serious Hi-Fi sources.

Independent HPF + LPF
Proper active crossover management for 2.1 systems.

4th-Order Butterworth HPF
Steeper main-speaker high-pass filtering for cleaner system integration.

3-Band EQ
Independent Bass, Mid and Treble adjustment.

Tone Bypass
Enjoy the signal without tone-control processing when preferred.

Extensive Inputs
USB, Optical, Coaxial, HDMI, Bluetooth, RCA and Balanced.

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Specifications

Specification	O-NOORUS D4 PRO
Amplifier Chip	Texas Instruments TPA3255
Amplifier Architecture	Class-D
Feedback Technology	PFFB (Post-Filter Feedback)
Output Power	Up to 200W × 2
Channels	2.0 Stereo
Subwoofer System	Dedicated Subwoofer Output
Main Speaker HPF	60Hz / 80Hz / 120Hz / Bypass
Subwoofer LPF	60Hz / 80Hz / 120Hz / Bypass
HPF Type	4th-Order Butterworth
Tone Control	Bass / Mid / Treble
Tone Adjustment	±12dB
Tone Bypass	Yes
HDMI	eARC / ARC with CEC
USB	Yes
Optical	Yes
Coaxial	Yes
Bluetooth	Yes
RCA Input	Yes
Balanced Input	Yes
Optical/Coaxial Resolution	Up to 24-bit / 192kHz
Power Supply	48V 5A GaN Adapter
Included Adapter	48V 5A GaN

Specifications are based on the manufacturer’s published information and may be subject to revision.

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What’s Included

• O-NOORUS D4 PRO Amplifier
• 48V 5A GaN Power Adapter
• Power cable/accessories
• Remote control
• User documentation

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Price

৳24,500

Includes 48V 5A GaN Power Adapter

Available from Gigabass Audio.

For customers looking for a compact amplifier that can serve as the center of a serious stereo, desktop, TV or 2.1 system, the D4 PRO offers an unusually complete combination of high-power TPA3255 amplification, HDMI eARC, balanced connectivity, advanced crossover management and flexible tone control.