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
- Sounds very similar to Pass Labs' top-of-the-line Xs series
- Effortless sound quality, even at full tilt, alongside a weight, solidity and unusual sense of depth
- Portrays musicians and their instruments as 3-D, full-size entities, realistically positioned left-to-right and front-to-back across the soundstage
- Offered better-defined lower bass, more weight, and a fuller midrange
- Massive build quality
Product Considerations
- Gets very warm during use due to Class A bias
- Sharp heat fins on the sides mean users should be careful to avoid injury
- Some reviewers indicate that stock power cable may not deliver peak performance
Comparisons (according to reviewers)
- Vs. Pass Labs Xs 300: Has less bass slam and a bit less 'sheen' on musical instruments in the high frequencies
- Vs. Merrill Thor mono blocks: Had better-defined lower bass, more weight and a fuller midrange, and wider perceived dynamic range, but the Thors had a slight edge in overall smoothness
- Vs. Krell units: Had superior bass slam, but showed their age in nearly every other category
Takeaway: The X600.8 is a powerful amplifier that delivers a high-end listening experience with a remarkable and full-bodied presentation. It offers stunning depth with realistic instrument layering, making it a worthwhile audition for serious audiophiles.
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Manufacturer details
- Type: Mono
- Gain (dB): 26
- Full Power @ 26 dB gain (V): 3.46
- Low Frequency Response: 1.5 Hz
- High Frequency Response: 100 KHz
- Power Output /ch (8 ohm): 600
- Input Impedance (SE & BAL Kohms): 50/100
- Damping Factor: 200
- Power Consumption @ Idle (Watts): 600
- Unit Dimension (W x D x H): 19 x 21.5 x 11 inches
- Unit Weight: 123 LBS
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:
- They design their products with a minimalist approach, focusing on essential components and avoiding unnecessary features in the signal path.
- Pass Labs emphasizes high-quality parts and meticulous assembly over brute force design, resulting in components built to last for decades.
- Their amplifiers often exhibit a sound signature with both detail and a touch of warmth, providing a musical and engaging listening experience.
- The company's components are often fully class-A, or run deeply in class A territory, known for its excellent linearity and lack of distortion.
Select products
INT-25
- Positioning: The entry-level integrated amplifier in the Pass Labs lineup, offering a more affordable option with high-quality sound.
- Description: Features simplicity and high-quality Class A amplification, making it ideal for small rooms or setups where space is limited. It features a minimalist design with fewer components in the signal path, which enhances speed and stability compared to more complex models like the INT-250. This makes it a great choice for those with a moderate budget who prioritize sound quality over power output, as it offers 25 watts per channel and is best suited for efficient speakers.
X350.8
- Positioning: The high-powered stereo amplifier positioned as the most powerful Class A/B amplifier in the Pass Labs lineup.
- Description: Delivers 350 watts per channel, providing ample power for larger rooms and more demanding speakers. It offers a superb and accurate representation of recordings, with a focus on holistic design rather than just specifications, setting it apart from smaller models like the X250.8.
XA200.8
- Positioning: A premium monoblock amplifier in the Pass Labs lineup, designed for high-end audio systems.
- Description: Delivers 200 watts of pure Class A power, providing exceptional sound quality and headroom for complex musical passages. It stands out with its high current capability and lack of microprocessor-controlled bias schemes, unlike the more affordable XA100.8.
XS300
- Positioning: The flagship monoblock amplifier in the Pass Labs lineup, representing the pinnacle of their amplifier technology.
- Description: Offers 300 watts of Class A power with separate power supply and amplifier chassis for lower noise, making it the top choice for those seeking the best in music reproduction. It features a higher-power constant-current source and single-ended bias current, which lowers distortion and enhances harmonic control compared to other models like the XA200.8.
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Pass Labs
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Product Strengths
- Ample power with minimal distortion
- Audionet's ULA (Ultra-Linear-Amplifier) technology, originally developed for medical engineering
- Impressive dynamic prowess and the ability to plumb the hidden depths of CDs and LPs
- Subtle musical and instrumental details come through cleanly and coherently, without compromising life-likeness of tone colors and harmonic expression
- Exceptional bass reproduction, with a rich, detailed, and uniform low end
Product Considerations
- Positive and negative speaker terminals are close together, requiring caution when connecting speaker cables
- Balanced input use involves an op-amp, which some believe impacts sound quality, single-ended inputs are preferred by some
- A preamp should be used to get the best sound from these amplifiers
- Display text changes locations randomly, which some may find distracting
Comparisons (according to reviewers)
- The Burmester sounded cleaner, airier, and more revealing, but could not quite compete with the AMP II MAX in authority over the bass frequencies and in blackness of the background
- The Pass Labs was tonally rich and pleasurably soft, plus the amp gave an extraordinarily punchy presentation, in that it bettered the performance of the AMP II MAXes, on the other hand, it was rather general in the organization of the soundstage and the background wasn't quite as black as with the AMP II MAXes
- Plinius shone in resolution, as well as delivered exceptionally dimensional soundstage and very neutral overall sound, especially in Class A mode, however, it did not have the same punch as the AMP II MAXes, and the sound wasn't equally gentle
- The McIntosh MC-501 delivered a richer and warmer sound, but with less power and extension than the AMP II MAX
Takeaway: The Audionet Max monoblocks offer a powerful and refined listening experience, making music sound engaging and detailed. Their ability to control speakers and reveal nuances in recordings makes them a great choice for serious audiophiles.
Video review
Our take on the brand
The 911 MK3 power amplifier is a close derivative of the reference power amp 909 and is regarded as one of the quickest and most powerful amps in the audio world. Its strong performance is the result of the knowledge and experience gained during the design and manufacture of the much-acclaimed 909 power amp. The MK3 moniker indicates that Burmester’s second largest power amp has reached its third generation of refinement. With the distinctive appearance of the silver anodized fins of its heat sinks the 911 MK3 exudes power and elegance. It tightly controls any bass driver and proves that there is a lot of musicality in the bass line. Excellent spatial resolution, detail and musical warmth characterize the sonic signature of the 911 MK3.
Product Strengths
- Neutral and grain-free sound, not like typical solid-state or tube amplifiers.
- Powerful and articulate bass, seamless and smooth mids, and extended, non-harsh highs.
- Exceptional build quality and a luxurious feel with immaculate laser-cut detailing and silver anodizing.
Product Considerations
- The glitzy appearance might be divisive.
- High-quality source components and speakers are required to perform at its best.
- The unit is large (almost 50cm wide) and very heavy (32kg), requiring a sturdy rack and careful handling during setup.
Takeaway: The Burmester 911 mk.3 provides exceptionally intricate, powerful, and dynamic sound, making it a very refined amplifier that is a treat for your ears. It is a top-performing amplifier made with great craftsmanship and build quality.
Video review
Our take on the brand
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Designing an amplifier that would outperform the Zions in bandwidth, output and transparency was a tall order. This amp would need to express all of ampsandsound's most closely held philosophies at an even higher level. More power or complex circuitry for the sake of increasing the cost was out of the question. Where does one go, once they've scaled Everest?
After extensive listening and research, the Citation II was settled on as the basis for the design. This amplifier was designed to be an amplifier in the tradition of Harry Pearson's Absolute Sound - something which had absolute fidelity resulting from the widest and flattest frequency response and as close to an absence of distortion as possible. This amplifier is the proverbial bigger gun for those customers who require even more power than a Zion.
The original Citation II, much like the Citation V, is underwhelming in the power supply. A significantly more robust version was in order, which can supply eight amps per channel, and allows for tubes capable of greater output than the original. This of course necessitated the design of the highest power input power transformer ampsandsound has ever designed. In the process of redesigning the power supply, careful attention was given to improving dynamics, RMS output, regulation and lower distortion.
Depending on the tube selection, the Arch will output between 60-100W in pure class A, and represents our absolute statement on power output. As with the Zion, everything on the Arch is capable of handling several times the rated output power of the circuit. The result is astonishingly low distortion, and a true-to-source amplifier with massive grip on loudspeakers.
The output transformer on the Arch has a practically unheard of bandwidth of 2hz to 110khz at -3dB. Even the excellent original Freed iron does not achieve these kind of figures under real world test conditions. Total output power is 65 watts with KT88s and 85watts with KT150s. The total power is the measure of this amplifier's magic - not because of the output, but because it achieves astounding frequency linearity and vanishingly low distortion while doing so.
A tube amplifier that can reliably reproduce frequencies lower than 20hz is unheard of and one that can descend into the low single digits is mythical. Perhaps most important is distortion figures that would be considered remarkable for a well designed solid state amp, accomplished in a tube amplifier without a single regulator.
The chassis is 10-gauge cold-rolled steel, which imparts even greater damping than the Zions and makes for an imposing amplifier. The choice of 10-gauge steel was born of our founders ability to make singular decisions on the basis of performance without consideration to costs. Each choice in the Arch came about in the same manner, and reflects a pursuit of absolute performance not a proxy vote for profits.
Each monoblock weighs in at around 100lbs, and represents the pinnacle of our philosophy: hand built on turret boards using ultra pure point-to-point wiring, with no expense spared in creation process or parts selection. Wiring assembly alone takes 18 hours per channel, and is done by hand, before inspection, break in, testing and validation.
This amplifier goes far beyond being a modification or clone of the Citation II. Instead, the Citation II serves as a touchpoint for an amplifier built to completely eliminate questions of output and distortion. The Arch is the pinnacle of the low distortion, high power spirit of the Citation amplifiers, and each unit is personally measured, tested and listened to by Justin Weber before shipping.
The sound of the Arch must be heard to be understood. Suffice to say, the Arch simply sounds like music, and demands partnering equipment of highest calibre. Please contact us if you wish to arrange a demo.
Product Strengths
- Incredibly nimble, with every detail highlighted, providing an extra layer of resolution
- Delivers all of the detail and clarity without the traditional fatigue
- The balanced input transformer properly sums the positive and negative legs of the balanced signal, and in so doing retains much of the benefits that you normally achieve with fully balanced amps—noise rejection
- The distortion numbers are exceptional for a tube amplifier
- Compatibility with nearly every commercially available speaker, due to the support of three impedances (4 ohms, 8 ohms, and 16 ohms), and output power exceeding 60 watts with KT88s, and 80 watts with KT150s
Product Considerations
- There are no modern reproductions of the 12BY7A, requiring matched pairs to run the amplifiers
- The bias is fixed—it's selectable between settings, but dialing in the distortion could not be simplified further
- Heavy at nearly 100 lbs each, as there's a lot of iron in both the transformers and the chassis work
- A hint of tube noise was present in one channel when no music was playing, likely specific to the tubes used
- Not a wise choice to any planer but complex crossovers and difficult loads have not compressed the amp in testing
Comparisons (according to reviewers)
- Vs ampsandsound Zion Monos: The Arch Monos are more neutral, faster, and provide an extra layer of resolution, compared to the richer and more harmonic sound of the Zions
- Vs TAD: The Arch is clean, powerful, and has many characteristics of very good solid-state amp, though the TAD approach was similarly neutral in many ways, albeit with a lightning quickness that the Arch did not have
Takeaway: The ampsandsound Arch Monoblock amplifiers are a technically proficient and beautifully built amplifier that delivers exceptional detail and clarity without fatigue. If one wants a vintage but modern sound, the Arch Monoblocks could be a good choice.
Video review
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What competes at this price?
Our Summary
Product Strengths
- Powerful, able to drive any speaker at any level with ease
- Delivers a new dimension in realism at any volume level, exposing the timbre of bass instruments unlike ever heard before
- Reveals harmonic quality of instruments and voices
Product Considerations
- Heavy, weighing 140lb (63.5kg), requiring assistance for moving and unboxing
- High running temperature (55-65oC across the chassis) and draws 500W from the wall when idle
- When speaker cables are terminated with spade lugs, caution is advised as the posts are close together
- Output is floating—it should not be connected to any loudspeaker with a grounded 'black' terminal
- BAT components take a long time to "break in" (400-500 hours of use)
Takeaway: The BAT REX 500 is a very powerful amplifier that drives speakers with ease and reveals new levels of realism in familiar recordings. It is a must-audition for those seeking reference-level power amplification.
Video review
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Our Summary
Product Strengths
- Delivers 350 watts into 2-ohm, 4-ohm, or 8-ohm loads
- The design has a purity that is quite amazing
- Effortless power
- Soundstage is big
- Transparent
Product Considerations
- Not necessarily suitable for pairing with extremely cold sounding, sterile or bright speakers
Comparisons (according to reviewers)
- MC3500 is more open and airy, with base not as hard fisted, compared to Krell KSA 250
- It compares with brands like soulution, big Audio Research, and CH Precision, but at a lower cost
Takeaway: The MC3500 is an impressive amplifier that delivers a natural and pure sound, able to drive almost any speaker. If you're in the market for a McIntosh amp, this is the one that makes music sound pure, simple and unadulterated.
Video review
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Our Summary
Product Strengths
- Prodigious bass output and rich tonality, especially for a solid-state design
- Great presence, a black background, and strong resolution playing effortlessly at very high volume levels
- Offers a wide, well-defined soundstage
- Beautifully designed with a luxurious appearance, relatively compact dimensions, and attention to detail in its internal layout
- Reserves of power will comfortably drive a wide range of speakers to high levels
Product Considerations
- Attacks can be slightly soft on some material
- The soundstage, while wide and well-defined, may lack the pinpoint accuracy and layered depth of some reference amplifiers
- Requires support beneath it on carpeted floors to allow sufficient airflow
Comparisons (according to reviewers)
- Vs soulution 511, the soulution 511 was faster and more accurately conveyed bass notes, threw an image with greater accuracy, and was more open on top
Takeaway: The Electrocompaniet AW 300 M is a gutsy and poised monoblock amplifier that delivers lots of power and handles a variety of speakers, giving an excellent listening experience. Its solid build and high performance make it a great choice for those seeking high-end audio quality.
Video review
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Our Summary
Product Strengths
- Great build quality that feels solid and built to last
- Impressive control, speed, and transparency in sound reproduction, resulting in a highly satisfying and natural sound
- Excellent bass grip, with precisely layered and insightful basslines
- Each instrument is distinct within the orchestra
Product Considerations
- Speaker cable terminals are a bit tight, especially with larger spades
- Software may need updates to ensure devices connect seamlessly
- Setup may be crucial to get the best sound
- According to one commenter, the treble can be hard and tiring
Comparisons (according to reviewers)
- The 861 exceeds the Moon 860A v2 in performance due to improvements in isolation, mechanical damping, and power supply
- The 861 has less pronounced colors than Burmester 218 amplifiers
- The 861 has more weight and oomph than Octave MRE 220 SE
Takeaway: The Moon 861 is a powerful and well-built amplifier that delivers a natural and detailed sound, with excellent control and dynamics. With its power and balanced sound, listeners may find themselves enjoying music even more.
Video review
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Our Summary
Product Strengths
- Outstanding design, reflecting over 50 years of experience
- Signals are amplified without adding even a hint of its own signature
Product Considerations
- Heavy amplifier (50 kg), so assistance may be needed when moving it
- May be overkill for smaller speakers, as it is Accuphase's most powerful amplifier to date
- Could be more revealing of the sonic characteristics of connected preamplifiers or variable output sources
Takeaway: The Accuphase P-7500 is a high-end stereo power amplifier that delivers clean and linear amplification, suitable for demanding speakers. Its robust build and excellent measurements ensure a neutral listening experience, making it a worthwhile investment for audiophiles.
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