Audio Research Reference 330M
The Reference 330M marries tube-rich tonal density with solid-state-like grip, unleashing thunderous bass, explosive dynamics and expansive three-dimensional imaging. HiFi News found its enormous reserves effortlessly controlled complex music, while SoundStage Solo praised its smooth, full-bodied precision. It is a statement monoblock for systems demanding scale without surrendering musical intimacy.
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Deliciously Crispy
Sound Quality
96/100
Build Quality
92/100
Value for Money
81/100
Pros
Delivers exceptional dynamic headroom, powerful bass slam and composed control with demanding loudspeakers.
Combines warm, saturated tube tone with clear detail, smooth treble and natural vocal presence.
Creates wide, deep and precisely focused soundstages with convincing image scale.
Auto-bias, valve-life metering, balanced and single-ended inputs, and 4/8-ohm taps simplify flagship tube ownership.
Cons
The purchase price is exceptionally high, placing it among a narrow field of flagship amplifiers.
Replacing the twelve output valves across a stereo pair adds significant long-term ownership cost.
At 101 lb per monoblock, installation remains a substantial physical undertaking; the high fan setting can be audible during quiet playback.
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What Reviewers Are Saying
SOUND QUALITY PERFORMANCE 96/100
Reviewers describe an unusually complete blend of tube richness, fine detail, massive-scale authority and spatial realism. The 330M repeatedly impressed with its ability to sound warm and emotionally involving without giving up the control, clarity or dynamic freedom associated with powerful solid-state amplification.
Transparency Resolution
95/100
HiFi News heard abundant detail and refinement, including vocal character, studio acoustic cues and prominent sibilance without loss of composure. SoundStage Australia also found complex bass lines cleanly separated, while Best of High End praised its combination of liquidity with razor-sharp clarity.
Tonal Balance Musicality
96/100
The presentation is consistently described as colorful, rich, warm and full, with convincing timbre and substantial image weight. Reviewers also stress that this generosity does not become sluggish or overly soft: highs and midrange remained smooth and well balanced, while voices carried exceptional presence and natural character.
Dynamics
97/100
This is a major strength. Reviewers report solid-state-like speaker control, explosive dynamic expression, devastating bass slam and the ability to sustain very high levels on complex music without strain; HiFi News measured more than 400W and dynamic peaks above 500W.
Soundstage Imaging
95/100
The 330M is credited with panoramic orchestral scale, sharply focused vocals and strong separation within dense arrangements. Stereophile heard an exceptionally wide and deep stage, while HiFi News described beautifully etched images and a solid, three-dimensional orchestral picture.
Assessments of Build Quality, Usability, and Overall Propositions.
Build Quality
92/100
Reviewers describe the 101lb monoblocks as beautifully designed, superbly assembled and engineered to a flagship standard. The fully balanced layout, high-quality 4- and 8-ohm terminals, automatic biasing, valve-life meter, practical handles and two-stage cooling show thorough attention to operation, though the audible high fan setting is a minor practical caveat.
Value for Money
81/100
At $90,000 per pair in the US, £92,000 per pair in the UK and approximately AU$170,000 per pair in Australia, these amplifiers compete in a very rarefied field of flagship alternatives. Reviewers admire the performance and speaker compatibility, but also note the substantial purchase price and the ongoing cost of replacing twelve output valves.
Reviews & Sources
Professional reviews and sources for this product's Watt'n Potatoes analysis.
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Specifications
- Power Output
- 330W @ 1kHz 0.92% THD +N 10Hz - 80kHz Unweighted1W @ 1kHz 0.013% THD+N 10Hz - 80kHz Unweighted
- Frequency Response
- (-3dB points at 1 watt) 0.5Hz to 110kHz
- Input Sensitivity
- 2.48V RMS Balanced for rated output; 1.23V RMS Single Ended for rated output135mV RMS Balanced for 1W output; 70mV RMS Single Ended for 1W output
- Gain
- 26.3dB Balanced Input into 8 ohms34dB Single Ended Input into 8 ohms
- Input Impedance
- 168.5k ohms Balanced, 19.5k ohms Single Ended
- Output Polarity
- Non-inverting. Balanced input pin 2+ (IEC-268)
- Output Taps
- 4 ohms, 8 ohms
- Output Regulation
- 0.82dB 8-ohm load to open circuit
- Output Impedance
- 0.812 ohms
- Damping Factor
- 10 at 8 ohms
- Noise
- Input shorted. Noise level referenced to 1W into 8 ohmsBalanced: -80dBV 10Hz-80kHz Unweighted; -91dBV A-weighted ;Single Ended: -75dBV 10Hz-80kHz Unweighted; -86.5dBV A-weighted
- Power Requirements
- 105-130VAC 60Hz (210-250VAC 50Hz) 987w at rated output;386w at idle, 1.1w power off
- Tube Complement
- 6 matched KT170 V1-V6 Power Output; (1) x 6H30 V7Gain Stage; (1) x 12AX7/ECC83 V8Gain Stage; (1) x 6550 and (1) x 6H30 V9, V10 voltage regulator
- Dimensions
- width 18.5” (47 cm) 19.0” (48.26 cm) inc faceplateheight 10.5” (26 cm)depth 21.5” (54.6 cm) with handles & connectors 24.25” (61.6 cm)
- Shipping Dimensions
- 31 x 27 x 20 (in). 787 x 686 x 508 (mm).
- Weight
- 101 lbs 46 kg, Shipping 118 lbs, 54 kg (per monoblock)
Manufacturer's Description — Audio Research
Reference 330M
Make music come alive in a way you will never forget.
The Reference 330M puts you right there, and does not let you forget that you are listening to a living performance captured in time, just waiting to be unearthed with no potential left unrealized.
The beauty, the emotion, the dynamics, the life are all there to conjure total immersion, whenever you want it.
A hand built masterpiece
The Reference 330M is the finest amplifier ever created by Audio Research, with the ability to control any loudspeaker with a vice-like grip and startling dynamic life. It is the culmination of everything we have learned over 50+ years.
It is a statement that music is king, always ready to sweep you away. Infusing new technology and circuits with the finest vacuum-tube architecture, the 330M elevates music reproduction to the highest plateau with an all-tube signal path.
From its ECC83 input to its KT170 output, with tube regulation in the power supply, the 330M proves that you can enjoy the ease of high power along with a delicacy and purity usually associated with low-power amplifiers. Tonal saturation and density accompany a specificity of recording space beyond anything we have built.
Liquidity and artistry abound, yet with blade-like edge precision when called for. Extension at both frequency extremes is state of the art even for solid state amplification. Statement-level loudspeakers capable of meaningful infrasonic bass output will be fully commanded down through their lowest octave without a hint of retreat. Stones unturned: None.
This is our heritage, the legacy created by our founder, William Zane Johnson.
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- 110Hz — online and in-store — Kielce, Województwo świętokrzyskie, Poland (website)
- 3mA Audio — online and in-store — Houston, Texas, United States (website)
- Absolute Sounds — in-store — London, England, United Kingdom (website)
- Alpha High End — online and in-store — Brasschaat, Vlaams Gewest, Belgium (website)
- Ambiance Concert — in-store — Angers, Pays de la Loire, France (website)
- American Sound — in-store — Richmond Hill, Ontario, Canada (website)
- Area Hifi — online and in-store — L'Eixample, Comunidad Valenciana, Spain (website)
- Aris Audio — in-store — Salt Lake City, Utah, United States (website)
- Audible Images — in-store — Melbourne, Florida, United States (website)
- Audio Advice — online and in-store — Raleigh, North Carolina, United States (website)
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