Amps vs. Preamps: What's the Difference? | Moon Audio

XA30.8 Stereo Power Amplifier

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30 watts per channel, Class A, world-class amplification. More details

Amps vs. Preamps: What's the Difference? | Moon Audio

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The Pass Labs XA30.8 Stereo power amplifier is a powerhouse of audio excellence that redefines the listening experience. The XA30.8 is a stereo amplifier capable of delivering 30 watts per channel into 8 ohms, featuring Pass Labs' signature Class A topology for unparalleled sound quality. Its symmetrical circuitry and meticulously selected components ensure pristine audio reproduction, revealing the subtlest nuances in your music. With a robust power supply and exceptional build quality, the XA30.8 effortlessly drives a wide range of speakers with authority and finesse. Equipped with balanced and single-ended inputs, this amplifier offers versatility and precision in its connectivity options. The Pass Labs XA30.8 is a true embodiment of audio craftsmanship, setting a new standard in high-fidelity amplification for the most discerning audiophiles.

Dragon Cable Recommendation: we recommend pairing the XA30.8 Power Amplifier with the Silver Dragon Interconnect. The Silver Dragon Interconnect is one of our best-selling cables at Moon Audio. Sold in Pairs, it is our top-of-the-line silver conductor-based interconnect. With a braided geometry and amazing shielding, this interconnect is a remarkable solution where noise isolation is key. The Black Dragon Power Cable is also recommended to provide the cleanest and unbridled power to your high-end amplifier.

The Pass Labs XA30.8 Stereo power amplifier boasts a range of features designed to deliver exceptional audio performance:

  1. Class A Topology: Utilizes Pass Labs' renowned Class A topology for pristine sound quality and low distortion.
  2. 30 Watts per Channel: Provides 30 watts of power per channel into 8 ohms, ideal for a wide variety of speakers.
  3. Symmetrical Circuitry: Ensures balanced and accurate audio reproduction, capturing the subtlest details in music.
  4. High-Quality Components: Meticulously selected components contribute to the amplifier's exceptional sound clarity and dynamics.
  5. Robust Power Supply: Features a robust power supply for stable and reliable performance.
  6. Versatile Connectivity: Equipped with both balanced (XLR) and single-ended (RCA) inputs, allowing for flexible system integration.
  7. Exceptional Build Quality: Crafted with precision and attention to detail, the XA30.8 is built to last and maintain its performance over time.
  8. Effortless Speaker Driving: Effortlessly drives a wide range of speakers, delivering authoritative and nuanced sound reproduction.
  9. Minimalist Design: The amplifier's sleek and minimalist design reflects Pass Labs' commitment to both aesthetics and audio excellence.
  10. Superb Audio Fidelity: Delivers superb audio fidelity, revealing the full potential of your music collection with unparalleled clarity and precision.

The Pass Labs XA30.8 stands out as an extraordinary stereo power amplifier with numerous high-end features. It utilizes high-biased MOSFETs for higher-power Class A operation, along with direct-coupled front-end circuitry that ensures exceptional stability. Additionally, it is equipped with larger, more robust heat sinks akin to those found in the larger .8 product line of Pass Labs amplifiers. While the list of features is extensive, experiencing the XA30.8 firsthand reveals its true value. It may very well represent a pinnacle of value, striking a perfect balance between performance and cost that aligns with your preferences.

"For me, listening to the XA30.8 is not unlike the first time I heard a really great stereo system; it is different, alive, and fantastic" - Gary Beard, Positive Feedback

Input Connection and Input Impedance

On the rear of the XA30.8 power amplifier, you'll find both single-ended (RCA) and balanced (XLR) input connections. On the single-ended input there is an impedance of 50 Kohms and 100 Kohms for the balanced input. If you are using the RCA inputs, then please use the gold-plated input jumper to short the (-) input (pin 3) of the XLR connector to ground (pin 1).

Output Connections and Safety Protocols

The Pass Labs XA30.8 power amp will efficiently and effectively power most loudspeakers on the market. With 30 watts per channel, the XA30.8 is a capable amplifier and will require a few steps to get acquainted with the connection protocol. Please note that both the red (+) output connection and the black (-) output connection are live. There is no ground reference at the speaker terminals. The black (-) speaker terminal must never be treated as the ground.

This is extremely important when connecting an active subwoofer to the amplifier's output. If you require a ground connection then please use the white ground terminal included on the rear panel. Also note that the white signal ground connection is not a safety ground. The safety ground is only provided by the power cable (detachable). You should never do anything to remove the safety purpose of the power cord or do anything to put the amplifier and your connected audio gear at risk.


  • HomeTheaterReview - Best of 2016 Award
  • Writers' Choice Award, 2015 - Positive Feedback

Pass Labs and First Watt

Pass Labs and First Watt were founded by hi-fi legend Nelson Pass. After co-founding and later selling Threshold Audio, Pass began working out of his Auburn, California, home in the early 1990s to develop prototypes of single-ended Class A amplifier designs under the name Pass Labs. Pass Labs quickly became known for its commercially produced Aleph, X, and XA Series amps, and preamps. Pass later started First Watt as a passion project focusing on low-power amps for a niche audiophile audience. Today, Pass splits his time between the two companies, with production happening in Pass Labs' facility in Foresthill, California.


What is the output power rating of the Pass Labs XA30.8 Stereo Power Amplifier?

The Pass Labs XA30.8 Stereo Power Amplifier is rated at 30 Watts per channel into 8 ohms and 60 Watts per channel into 4 ohms. While this may seem modest compared to higher-powered amplifiers, the XA30.8 is designed for high-quality, low-power amplification. It excels with high-efficiency speakers, offering a clean, detailed, and dynamic sound reproduction even at lower volumes.

What distinguishes the Pass Labs XA30.8 from other amplifiers in the Pass Labs lineup?

The Pass Labs XA30.8 is known for its Class A operation and exceptional sound quality. It is a pure Class A amplifier, meaning it operates in Class A mode at all times, providing a warm, natural, and engaging sound signature. The XA30.8 also features a dual-mono design with a separate power supply for each channel, ensuring excellent channel separation and imaging. Its low distortion and high-current delivery make it an ideal match for high-quality speakers.

Can the Pass Labs XA30.8 drive difficult speaker loads?

The Pass Labs XA30.8 is designed to drive a wide range of speaker loads effectively. It is particularly well-suited for high-efficiency speakers that benefit from its Class A operation and high-current capability. The XA30.8's 30 Watts per channel into 8 ohms and 60 Watts per channel into 4 ohms provide ample power for many audiophile-grade speakers, delivering a clean and dynamic sound with excellent control.

Does the Pass Labs XA30.8 require any special considerations for setup or maintenance?

The Pass Labs XA30.8 Stereo Power Amplifier is relatively straightforward to set up and operate. It does not require bias adjustments, as it is a self-biasing Class A design. However, users should ensure proper ventilation for optimal performance, as Class A amplifiers can generate heat. Adequate ventilation will help maintain the amplifier's performance and longevity. Additionally, it is recommended to provide sufficient space around the amplifier for airflow and to follow Pass Labs' guidelines for safe and optimal operation.

Who is Nelson Pass?

Nelson Pass, the man behind Pass Labs and First Watt, has been designing and building amplifiers for decades. His early passion, however, was speakers; at age 14, he started assembling loudspeakers. As a college student studying physics at the University of California-Davis, he co-founded a speaker company called PMA. He also worked for ESS, where he designed crossovers and enclosures. After college, with his interest having shifted toward amplifiers, Pass co-founded Threshold Electronics (now Threshold Audio). His achievements during the Threshold years include developing the first dynamically biased Class A amplifier circuit; developing a fully cascode audio power amplifier; and developing the STASIS stereo preamplifier and power amplifier. During the 1980s, Pass designed the Adcom GFA-555 amplifier. Later, after selling Threshold, he started Pass Labs in 1991 and First Watt in 1997. Pass holds several patents related to audio circuits.

How did Pass Labs make its name?

Pass Labs helped popularize solid-state, Class A power amplifiers. Pass Labs' first product, the Aleph 0 amplifier, operated as single-ended Class A up to its 70 watt rating and in push pull Class A at higher wattage. The Aleph series of amplifiers, some of the first solid-state amps that were said to be "tube-like" in sound, operated pure class A and contained internal circuitry using MOSFETs. The Aleph amplifiers had a unique appearance, a cube with heat sinks on all four sides, a solution to the heat generated by the class-A design. This can be attributed primarily to the specific MOSFETs used and the minimum number of gain stages that were implemented in the design. Pass Labs also developed the Super-Symmetry™ ("Su-Sy") circuit, which achieves exceptionally low distortion and noise levels. In 1998, Pass Labs released the X1000, the first amplifier using the patented SuperSymmetric™ topology. The X1000 achieved 1000 watts with high performance, local feedback and only two gain stages: a cascoded differential pair of transistors and a large bank of complementary output followers. This groundbreaking design informed all subsequent Pass Labs amplifiers.

What else does Pass Labs make?

In 2002, Pass Labs unveiled the first XA amplifiers, combining the X and Aleph topologies into balanced single-ended Class A amplifiers with many of the characteristics of both the X and Aleph series. The current Pass Labs lineup includes Class A amps (XA and Xs Series), Class AB amps (.8 Series), line preamps (Xs and XP Series), phono preamps (Xs and XP Series), integrated amps (INT Series), and one headphone amp.

What is the relationship between Pass Labs and First Watt?

When he started Pass Labs, Pass did everything out of his home. In 1997, having outgrown the space, Pass Labs moved into commercial space in Foresthill, California. When Pass started First Watt, it was a "kitchen table" venture, with work once again happening in his home. In 2016, with production demands not leaving him enough time to pursue the vast array of yet-to-be-designed amps, Nelson handed the business end of First Watt over to Pass Labs. Pass Labs took over the building of First Watt amplifiers as well as marketing and distribution. There's a synergy between the two operations, in that Pass Labs gets to gather up some of the more interesting First Watt finds and repurpose them as more commercially viable designs. Today, Pass splits his time between First Watt and Pass Laboratories.


Gain (dB)
Full Pwr @ 26 dB gain (V)
Low Frequency Response
1.5 Hz
High Frequency Response
100 KHz
Power Output /ch (8 ohm)
Power Output /ch (4 ohm)
Distortion, (1 KHz, full power)
Maximum Output (Volts)
Maximum Output (Amps)
Input Impedance (SE & BAL Kohms)
50 / 100
Damping Factor
Slew Rate (V/uS)
Output Noise (uV)
Input CMRR (dB)
DC Offset (V)
Leaves Class A at pk Watts:
Current Draw @ Idle (Amps)
Power Consumption (Watts)
Temperature (deg C.)
Unit Dimension (W x D x H) (In.)
19 x 21.25 x 7.5
Unit Weight (LBS)