British hi-fi brand Quad has announced the return of two of its most revered audio components: the Quad 33 preamplifier and the 303 stereo power amplifier. These reimagined units, originally launched in 1967, have been revamped for a modern audience while retaining much of the charm and innovation that made them popular over 50 years ago.

The 33 preamp and 303 power amp were groundbreakers when first introduced (check out our review from 2009), establishing transistor-based amplification as a viable alternative to valve amplifiers, which dominated the high-end audio scene at the time. 

Quad's designs were unique not only in their performance but also in their visual appeal. The original models' influence even reached the Museum of Modern Art in New York, where the 33/303 combo is part of the collection. Today, Quad seeks to honor this legacy while introducing key upgrades to meet contemporary audio standards.

The original Quad 33 and 303 were notable for separating the preamplifier and power amplifier into two distinct units. This design choice was unusual in the 1960s when most transistor amps were integrated systems. Quad’s decision to revive the 33 and 303 in 2024 stays true to the essence of the original designs, with subtle enhancements.

Visually, the new Quad 33 retains its compact form with a familiar grey finish, though the tone has shifted from the original taupe to a more modern matte silver. Orange accents, a hallmark of the original, have been modernized with LEDs to illuminate the controls. An LCD display, backlit in orange, adds to the retro-futuristic aesthetic while offering modern conveniences like dimming or switching off the backlight entirely.

The new 303 stereo power amplifier continues the tradition of vertical orientation, with the distinctive heatsink fins at the front. These have been slightly updated, with ten squared-off fins compared to the original eight. The overall appearance retains the understated elegance that Quad amplifiers are known for, with additional features like an orange standby button that ties the new 303 visually to its preamplifier counterpart.

While the visual design honors the original, the internal components have been updated significantly. The 2024 versions of the Quad 33 and 303 incorporate advancements in circuit design and materials that were unavailable in the 1960s.

One of the major innovations of the original 303 power amplifier was its "triples" output stage, a design that minimized thermal instability and reduced distortion. Quad has preserved this design in the new 303, while updating the components to deliver better performance. 

The new amplifier uses a low-noise, custom toroidal transformer that improves thermal stability and reduces distortion even further, making the amp both powerful and efficient. Rated at 50W per channel into 8Ω (up from the original 45W), the new 303 can deliver a maximum current of 10A, which allows it to handle more demanding speaker loads.

The preamplifier, too, benefits from modern advancements. The 2024 edition of the 33 features an entirely new circuit design, utilizing higher-quality components that provide superior sonic performance. A low-noise phono stage with adjustable gain for MM and MC cartridges, combined with precision RIAA equalization and an upgraded power supply, ensures that vinyl playback is crisp and detailed. 

The new 33 also includes a dedicated headphone amplifier, a feature absent from the original. This headphone amp uses a current-feedback design that delivers dynamic sound suitable for a wide range of headphones.

The new 33 and 303 models have been updated to support modern audio setups. Gone are the original’s DIN sockets, replaced by RCA and balanced XLR inputs and outputs, which provide more versatile connection options. The 33 preamp offers four line-level inputs (three RCA and one XLR) and a phono input.

It also features a USB port for firmware updates, reflecting the shift towards digital control in the user interface, even though the signal path remains purely analog. For added convenience, both units feature 12V trigger inputs and outputs, allowing them to power on or off in sync with other components in an audio system.

The 303 power amplifier also offers an upgrade path for users looking for more power. Two 303 amplifiers can be connected in bridged mode, converting each stereo amp into a mono amplifier, which can drive a single speaker. In this configuration, the power output increases to 140W per channel into 8Ω, providing more control and headroom for larger speakers or more demanding listening environments.

The original 33/303 combination was admired for its warm, detailed sound—a hallmark of Quad’s approach to transistor amplification. Early solid-state amps were often criticized for sounding harsh, but the 33 and 303 were known for their smooth, almost valve-like sound. This characteristic has been retained in the new editions, with improved clarity and dynamic range thanks to modern components.

The 33 preamp introduces a tilt control, a feature developed by Quad’s founder, Peter Walker, in the 1980s. Unlike traditional bass and treble controls, the tilt control adjusts both ends of the frequency spectrum simultaneously. This allows users to fine-tune the tonal balance without coloring the sound. Independent bass and balance controls are also available, providing more precise adjustments to match the listening environment.

The Quad 303 power amplifier, with its revised Class AB design and advanced feedback topology, promises to deliver the same smooth and richly detailed sound as the original, but with added clarity and stability. The amp is cool-running and compact, making it ideal for home or studio use. Its modest power rating may seem low by today’s standards, but its high current delivery means it can handle complex speaker loads with ease, maintaining its sonic finesse even under demanding conditions.

The 2024 editions of the Quad 33 preamplifier and 303 power amplifier will be available from authorized Quad retailers starting in mid-November. Each unit is priced at £1,199 in the UK, €1,499 in Europe, and $1,599 in the United States.