OSD Audio SMP300 Mono Subwoofer Amplifier - 300W
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Delivery £4.50 or Free Over £50
Delivery £4.50 or Free Over £50
All orders to mainland UK over £50 are eligible for free standard delivery.
For orders under £50 we have delivery rates starting from just £2.99
Need it fast? No problem, you’ll find express next day delivery rates available on most products. Learn More
60 Day Returns + 2 Years Warranty
60 Day Returns + 2 Years Warranty
We’re so confident that you’ll be happy with your purchase that we’ve extended our returns policy to 60 days.
We call it the “Happy Sound Guarantee”.
If you’re not happy with your purchase for any reason simply send it back to us for a full refund. Learn More
Warranty
K&B Audio are authorised dealers for OSD Audio. All sales come with a 2 Years manufacturers warranty and full technical support.
Description
Description
Enhance your home audio experience with the OSD Audio SMP300, a powerful 500W mono-channel Class D subwoofer amplifier engineered to deliver deep, clean bass with outstanding efficiency.
Perfect for home cinema systems, custom installations, or high-end two-channel audio setups, this compact yet robust amplifier is tailored for audiophiles who want to power a passive subwoofer with precision and control.
With its rack-mountable design and advanced signal sensing, the SMP300 integrates seamlessly into AV systems.
Whether you're upgrading a home theatre or adding low-frequency impact to a multi-room setup, this amplifier offers versatile performance with intuitive controls and flexible inputs.
FEATURES
- High Power Output: Delivers up to 500W peak and 300W RMS, driving even large passive subwoofers for room-filling bass.
- Class D Efficiency: Class D digital amplification ensures cooler operation and reduced power consumption without compromising on performance.
- Variable Crossover & Phase Control: Fine-tune your bass response to suit your room acoustics and speaker setup with adjustable crossover and 0–180° phase switch.
- Multiple Input Options: Includes both line-level and speaker-level inputs, making it compatible with a wide range of audio systems.
- Auto-On Signal Sensing: Automatically powers on when a signal is detected and shuts off after inactivity, improving energy efficiency and convenience.
- Rack-Mountable Design: Fits neatly into standard AV racks with removable side brackets, perfect for professional or custom home installations.
- Subwoofer EQ Switch: Enhances low-end performance with a tailored EQ setting for even deeper bass output.
- Heavy-Duty Build Quality: Solid construction with reliable components ensures long-term durability and consistent performance.
- Quiet Fan Cooling: Internal fan keeps the amp cool under load while maintaining quiet operation.
- Protection Circuitry: Built-in safeguards protect against short circuits, overheating, and overloading, giving you peace of mind.
Key Features
Key Features
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InputsRCA
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OutputsSpeaker Terminals
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Warranty
Specifications
Specifications
What You Get
What You Get
Downloads
Downloads
Payment & Security
Secure Payments
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
Authorised Dealer
K&B Audio are authorised dealers for OSD Audio. All sales come with a 2 Years manufacturers warranty and full technical support.

Why K&B Audio
Over a Decade of Experience
Established in 2013, we’ve been helping customers enjoy hassle-free home audio for more than 10 years.
Shop with Confidence
Our 'Happy Sound Guarantee' guarantees you expert advice, 60 day returns and free delivery on orders over £50.
35,000+ Satisfied Customers
We’ll always help you find the right solution for your needs, not just what boosts our bottom line. Don’t just take our word for it – read our glowing customer reviews.
Extensive Product Range
With the top brands, carefully curated bundles and thousands of home audio products in stock, we’ve got something for every setup.