Note that this is a discontinued product. You may want to visit the brand's page here to browse their newer products.
What reviewers think
Bloggers and YouTubers have tried this product—so we've summarized their strongest opinions below. Links to full reviews follow.
Product Strengths
- Fully balanced design, handcrafted in the USA
- Employs a sextet of KT170 valves, ECC83, and 6H30, with hand-selected and matched valves
- Features Audio Research's 'Auto-Bias' circuitry and an internal hour meter for monitoring valve usage
- Aesthetically elegant design with unique 'Ghost Meters' which are LED-illuminated and can be dimmed or switched off
- Capable of delivering high power at low frequencies, controlling and driving speakers like a big solid-state amplifier
Product Considerations
- High price point
- Requires a 20A IEC cable (supplied)
- The bass control and sheer bass output of the Gryphon Audio Antileon EVO (solid state) could not quite be matched by the Reference 330M
- The unit use a variable speed fan, although it was essentially silent during testing, this may still present a point of concern for some users
Comparisons (according to reviewers)
- Vs Gryphon Audio Antileon EVO: The Gryphon Audio Antileon EVO (solid state) has slightly better bass control and output
Takeaway: The Audio Research Reference 330M is an intelligently engineered and beautifully styled amplifier that embodies the meaning of 'Reference' in sound quality. Its powerful valve design delivers excellent performance and is sure to be a conversation piece in any high-end audio setup.
All
Reference 330M
reviews

Manufacturer details
- Power Output: 330 watts
- Tube Compliment: (6) KT170 Power Output, (1) ECC83 & (1) 6H30 input, (1) 6550 & (1) 6H30 Power Supply
- Inputs: XLR & Single-Ended
- Output Taps: 4Ω, 8Ω
- Tube Biasing: Auto-Bias
- Controls: 12V Triggers, RS-232, Remote Control, Power Saving Standby Mode
- Weight: 101 Ibs
Brand highlights
Taking a step back to look at reviewers' thoughts of the brand's entire lineup—not just this product—what stands out most is the following:
- Audio Research employs a design philosophy of cascading technological advancements, with innovations first appearing in their top-tier Reference series, then trickling down to the more accessible Foundation series.
- A unique aspect of Audio Research's digital products is their use of separate, optimized digital pathways for PCM and DSD signals, ensuring the highest quality conversion for each format.
- The use of vacuum tubes in the analog output stage is a core characteristic, contributing to a distinctive midrange fluidity and timbral accuracy designed to minimize the harshness often associated with digital audio.
- While embracing modern features like user-selectable upsampling and digital filters, Audio Research prioritizes sonic balance and accuracy, aiming for a sound that is neither overly warm nor bright, but fundamentally "right."
Select products
I/50 Integrated Amplifier
- Positioning: The entry-level integrated amplifier in the Audio Research lineup.
- Description: Offers a compact design with a powerful all-tube amplification circuit, making it ideal for small to medium-sized rooms. Features optional DAC and phono modules, providing flexibility for various audio sources, unlike the more specialized power amplifiers in the lineup.
VT80 SE Stereo Amplifier
- Positioning: A mid-range stereo amplifier, offering a balance between performance and affordability.
- Description: Uses KT150 tubes for a robust output, suitable for diverse speaker setups. Provides a fully balanced design, unlike the I/50, and is more powerful.
Reference 160S Stereo Power Amplifier
- Positioning: A premium stereo amplifier, designed for serious audiophiles.
- Description: With its dual GhostMeters and advanced auto-bias technology, provides superior soundstage and detail. Offers more power and flexibility than the 80S.
Reference 330M Monoblock Power Amplifier
- Positioning: The flagship monoblock amplifier, representing the pinnacle of Audio Research's engineering.
- Description: Combines groundbreaking technology with an all-tube signal path, offering unmatched control and dynamic range. Surpasses the 160M MKII in power and sophistication, making it the ultimate choice for those with no budget constraints and a desire for the best possible sound.
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