QX-300 Series Commercial Power

The QX-300 series amplifiers take commercial audio to a new level. The superior Class-D technology combined with small form factor make the QX-300 series the perfect solution for any commercial or industrial application. Wall and table mount options offer more flexibility, 10 units can be mounted in 3RU, achieving extremely high power to channel count for density.

UMAC™ Class-D technology delivers unequalled audiophile specifications, including the highest dynamic range and the lowest distortion performance of any comparable pro audio amplifier. This makes the QX-300 Series suitable for pro audio applications and for use in Hi-Fi and AV products.

Quest QX-300A


  • High Performance 2 x 150W Power Amplifier
  • Auto Load Sensing: 4-16 Ohm, 70V Line (Stereo) 100V Line (Bridged-Mono)
  • Energy smart technology (Green Energy Star & ErP 1275/2008/EC compliant)
  • UMAC™ Class-D – full bandwidth PWM modulator with ultra-low distortion
  • DanteTM/AES67 inputs available* (D version)
  • Individual volume control, standby, 80Hz High Pass Filter

  • Short circuit protection, DC protection, under voltage protection, temperature protection, overload protection
  • UREC™ universal mains switch mode power supply with Power Factor Correction (PFC) and integral standby converter
  • Rack-mountable 1RU 1/3 space, wall and table mount options available
  • Euroblock style amplifier I/O connectors
  • High Dynamic range incorporating, DynamiQ Bass technology®
  • Designed, Engineered, and Assembled in Australia

Energy Conserver

When in standby the QX-300A draws less than 0.5W of power, making the QX-300A series both Green Energy Star & ErP 1275/2008/EC compliant. Low-Z (4 -16 Ohm) operation and High-Z (70/100 V) loudspeaker configurations are catered for and adjusted using the onboard auto load sensing technology.


Made in Australia

Like all Quest products, the QX-300 Series is made to survive in a tough world.

Australian QC and advanced design engineering mean years of trouble free service in professional applications. The QX-300 Series provides a price/performance ratio that is hard to beat.


Installation Accessories

Included 1RU Brackets Included 1RU Brackets Included 1RU Brackets Included 1RU Brackets


Frequency Response 20-20kHz (+/-0.3dB)
Peak Output Current 25A
Dynamic Range 112dB (A-weighted)
Noise Level -76dBu (A-weighted)
Distortion (1kHz@1W/8Ohm) 0.003%
Distortion (1kHz@50W/8Ohm) 0.011% (Stereo) 0.004%
Crosstalk (1kHz@1W/8Ohm) -95dB
Gain 26dB/32dB
Maximum Input Level +24dBu
Amplifier Version QX-300A QX-300D
Input Type Phoenix Balanced Inputs Dante RJ-45 (AES67 Compatible) with RJ-45 Link
Input Sensitivity +7dBu/+4dBu -4.5dBFS/-1.5dBFS
Input Impedance 10kOhm -
Maximum Input Level +24dBu 0dBFS
Output Resistance 22.5mOhm/43.6mOhm
Front Controls Volume Adjust, 80Hz HPF Enable, Bridged-Mono Enable, Limiter Enable, Auto-Standby Enable)
Indicators (LEDs) Blue/Orange Active/Standby
Orange Protection
Green Signal
Orange/Red Limiter/Clip
Cooling Fan cooled, temperature dependent
Features Wake On Music, Auto-Mute (1ms wake-up), Limiting on High Temperature
Amplifier Protection Systems Thermal protection, Over- Current Protection, DC Protection, HF Protection
Mains Input Voltage Range 85VAC - 265VAC
Amplifier Version QX-300A QX-300D
Standby Power Consumption 0.4W 2.5W
Muted Power Consumption 4.2W 6.5W
Idle Power Consumption 7.2W 9.5W
Standard Power Consumption (Pink Noise@ 1/8th Rated Power, 8Ohm) 28W 30W
Mains Connector Standard IEC C14
Dimensions (H x W x D) 44.5 x 140 x 330 mm (1.75 x 5.5 x 13")
Weight 1.6kg (3.5 lbs)
Accessories Mains Cable, Feet, User Manual, Phoenix Plugs, Rack Ears

OPERATION MODES Stereo Mode Bridged-Mono Mode
LOAD 8Ohm 4Ohm 8Ohm 4Ohm 70V (22Ohm) 100V (33Ohm)
MAXIMUM CONTINUOUS POWER (@1KHZ, 1% THD) 2 x 140W 2 x 140W 1 x 280W 1 x 260W 250W 240W
MAXIMUM DYNAMIC POWER(@1KHZ, 1% THD) 2 x 200W 2 x 275W 1 x 550W 1 x 550W 550W 550W


* All specifications were measured at 240VAC

** Quest Engineering reserves the right to make changes in specifications, or products without prior notice.

*** The figures shown above are ‘real world’, usable specifications and are conservative as a result. Quest Engineering does not believe in portraying misleading or exaggerated specifications.


Contact Quest

Phone: +61 (0) 3 8373 6868

Address: 86 Derby Street, Pascoe Vale VIC 3044 Australia

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Feel free to get in touch with your nearest distributor. We’re always happy to hear from people interested in our products and we’re always ready to help you with your next project. You can find your nearest Quest distributor on the map below.

Contact Form

For general enquiries email Quest Directly using the enquiry form below.