Quad 303 Power Amplifier

A compact class-AB power amplifier with 50 Wpc stereo output, bridged mono operation, balanced and single-ended inputs, custom 200 VA toroidal transformer, and Quad’s triples output stage

The Quad 303 is a modern return to one of the most recognizable power amplifiers in British hi-fi. Designed to partner with the Quad 33 preamplifier, the new 303 keeps the visual identity and practical spirit of the original while updating the circuitry, build quality, connectivity, and speaker-driving capability for contemporary systems.

Rated at 50 Wpc into 8 ohms and 70 Wpc into 4 ohms, the 303 is designed for domestic hi-fi systems using moderately efficient loudspeakers, including Quad’s own electrostatic designs. It can also be switched into bridged mono mode, delivering 140 W into 8 ohms or 170 W into 4 ohms when used as a monoblock amplifier.

Classic Quad Power

The original Quad 303 became known for honest power, reliability, and musical ease rather than brute-force specification-chasing. The new 303 follows the same thinking, with a class-AB amplifier section and custom 200 VA toroidal transformer in a compact, cool-running chassis.

Its anodized chassis and CNC-routed heatsinks give the amplifier the unmistakable Quad look while providing a solid structure that resists interference from external vibration.

Triples Output Stage

The Quad 303 uses Quad’s symmetrical triples output stage, developed to provide a fully symmetrical output section, reduce distortion, and keep the resting current independent of output transistor temperature.

The new version updates the original concept with a fully complementary output stage, improving linearity, bias stability, and stability under high-voltage and high-current conditions. Premium power transistors support excellent gain linearity and dynamic range.

Stereo or Bridged Mono

In stereo mode, the 303 delivers 50 Wpc into 8 ohms and 70 Wpc into 4 ohms. For systems requiring more power, the amplifier can be switched into bridged mono mode, where output rises to 140 W into 8 ohms or 170 W into 4 ohms.

This flexibility allows the 303 to operate as a compact stereo power amplifier or as one half of a higher-output monoblock pair.

Modern Connectivity

The Quad 303 includes both single-ended RCA and balanced XLR inputs, making it easy to partner with the Quad 33 preamplifier or other modern preamps. It also includes a 12 V trigger input, 12 V trigger link output, and high-quality speaker binding posts.

About Quad

Founded in London in 1936 by Peter Walker, Quad has built its reputation on disciplined engineering, practical design, and the enduring goal Walker described as “the closest approach to the original sound.” Originally focused on amplifiers and public-address equipment, the company moved to Huntingdon, Cambridgeshire, in 1941, where Quad’s British engineering, service, and development remain centered today.

Quad’s history includes some of the most important products in British hi-fi, from the Quad II amplifier and the 33/303 preamp and power amplifier combination to the 405 current-dumping amplifier. In 1957, Quad introduced the world’s first production full-range electrostatic loudspeaker, establishing a loudspeaker lineage that continues through generations of ESL designs.

Today, Quad continues to balance heritage and renewal, developing electronics and loudspeakers that respect the company’s classic design values while addressing modern listening habits. Across its amplifiers, digital components, and loudspeakers, Quad remains defined by clarity, restraint, and engineering purpose.

Features

• Modern version of the classic Quad 303 power amplifier
• Designed to partner with the Quad 33 preamplifier
• Class-AB power amplifier section
• Quad symmetrical triples output stage
• 50 Wpc into 8 ohms and 70 Wpc into 4 ohms in stereo mode
• 140 W into 8 ohms and 170 W into 4 ohms in bridged mono mode
• Stereo/bridge mode selection
• Custom 200 VA toroidal transformer
• Fully complementary output stage
• Premium power transistors
• Single-ended RCA input
• Balanced XLR input
• High-quality speaker binding posts
• 12 V trigger input
• 12 V trigger link output
• Anodized chassis with CNC-routed heatsinks
• Classic Quad Grey finish

Included Accessories

• Power cord
• Remote control
• User manual

Specifications

Power Output (Stereo 8 ohms, Stereo 4 ohms, Bridged 8 ohms, Bridged 4 ohms): 50 Wpc, 70 Wpc, 140 W, 170 W

Power Amplifier Section: Class-AB

Core Technology: Quad 303 triples output stage, custom 200 VA toroidal transformer, stereo/bridge mode selection

Inputs: 1 line, 1 XLR

Outputs: 1 stereo speaker, 1 12 V trigger, 1 12 V trigger link

Power Amplifier Gain: 29 dB

Power Amplifier Input Impedance (Line, XLR): 15 kohms, 22 kohms

Power Amplifier Input Sensitivity (Line, XLR): 700 mVrms, 1.5 Vrms

Power Amplifier Signal-To-Noise Ratio: >108 dB, A-weighted

Maximum Output Current: 10 A

Standby Power Consumption: <0.5 W

Dimensions (HLW): 6.93" × 12.80" × 4.72" (176 × 325 × 120 mm)

Weight: 18.52 lb. (8.4 kg)