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
- Delivers an increase in audible detail, width and depth, and noticeable musical smoothness, especially on Hi-Res Jazz and Classical
- Retains the bass slam and ability to deliver significant horsepower, suitable for various music genres
- Provides tremendous depth and detail in the lower octaves
- Yields an addictively lush and natural midrange performance that can compete with the very best tube amplifiers
- High frequencies have a rich sonic texture and reach further back into the inner density and layers of the most difficult instruments, with impressive extension and plenty of jump factor and transient speed
Product Considerations
- The X350.8 is a heavy unit, requiring two people to lift safely
- High power consumption at idle (550 watts)
- The X350.8 runs a bit warm
Comparisons (according to reviewers)
- Vs Pass Labs X350.5: The X350.8 has a tighter—and possibly more accurate—bass performance
- Vs Pass Labs X350.5: The X350.8 has more refined higher frequencies with a moderate but noticeable improvement in purity and balance
- Vs Pass Labs X350.5: The X350.8 relays an increase in space impression and a softening of the cool transients, making various instruments a bit more musical and less analytical
Takeaway: The Pass Labs X350.8 is a high-powered amplifier that delivers detailed and smooth sound across a wide range of music genres, with the power to drive almost any speaker. It is a well-built amplifier and could be a great choice for audiophiles seeking ultimate performance.
All
X350.8
reviews

Manufacturer details
- Type: Stereo
- Gain (dB): 26
- Full Power @ 26 dB gain (V): 2.65
- Low Frequency Response: 1.5 Hz
- High Frequency Response: 100 KHz
- Power Output/ch (8 ohm): 350
- Input Impedance (SE & BAL Kohms): 50/100
- Damping Factor: 150
- Power Consumption @ Idle (Watts): 600
- Unit Dimension (W x D x H): 19 x 21.5 x 11 inches
- Unit Weight: 127 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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Used
Pass Labs
What if you spend more?
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
Our take on the brand
The Progression S350 Stereo Amplifier adds a potent stereo option to the Progression family. Leveraging our innovative Super Rail circuitry, the Progression S350 Stereo Amplifier exploits this unique technology delivering remarkable control and fidelity to any connected loudspeaker.
Every amplifier employs a voltage rail, actually two, a positive one and its companion negative partner. Voltage rails support the delivery of power to the speaker. The music signal swings between these two rails but due to natural loss, the musical signal never reaches the output rails' full capability.
Our Super Rail overcomes this limitation. Borrowing the idea of a turbo in a car engine, the Super Rail employs higher voltage rails in the sections prior to the output stage. This voltage "boost" allows the musical signal to exploit the full capability of the output voltage rails.
Extending the musical signal swing closer to the output rails maximizes the performance of the output circuitry design itself. The result is improved dynamics, lower distortion, and a fierce grip of the speaker.
Our summary
Product Strengths
- Superb sound quality makes listening to music an event
- Extraordinary frequency extremes with extended, natural-sounding treble
- Epitome of transparency, revealing details in recordings
- Impressive technology, including Super Rail circuitry, enhances dynamics and reduces distortion
- Visually appealing with a Swiss watch-inspired design and a large, responsive power meter
- Balanced-only connectivity might be a limitation for some users, though unlikely with high end preamps
Product Considerations
- Very heavy (115 pounds) and requires assistance to move—lacking handles
- May be overkill for high-sensitivity speakers
Comparisons (according to reviewers)
- The Progression S350 is on the harsher side, while Griffon Diablo 333 is more warm and balanced
Takeaway: The Progression S350 amplifier provides an outstanding listening experience. It has great transparency and reveals lots of detail in the music.
Video review
Our take on the brand
The Nu-Vista PAS features the tried and tested Nu-Vista stage featuring 6S51N nuvistors in a discrete class A amplifier buffer. This is followed by a balanced configuration circuit and balanced input high power, low distortion output amplifier stage. The power stage has 5 pairs of high power thermally compensated output devices for reliable and stable operation. Based on Titan 1000W stage, it has separate capacitors for bulk supply, and one each for output devices con siderably reducing output impedance and improving dynamics. Chokes are added for further improved supply ripple and pulse current spike reduction Bias is set for over 5W of initial class A operation thereafter the stage slides into class B operation at a point where the now much lower discontinuity is easier dealt with than “standard” crossover distortion.
Product Strengths
- Exceptionally well built, luxuriously finished with a thick-panelled milled aluminum chassis and first-rate metalwork quality
- Offers satisfying dynamic overtness and excellent transparency to the signal
- Provides exceptional detail retrieval and reveals amazing venue ambience and reverberance
- Offers a solidity and tight punch in the low-end, without artificial bloom or smearing of bass notes
- Features a two-chassis architecture, providing total quietness of the circuit
Product Considerations
- The diameter of each speaker connector's central post is too large, banana plugs are the only practical and safe way to connect speakers
- Stay away from brash metal tweeters and bad recordings, the Nu-Vista PAS will expose their failures
- The Musical Fidelity may not sound quite as fluid, but it's a more direct presentation, a more present—explicit sonic signature that provides exceptional detail retrieval compared to the Gryphon Audio Antileon EVO reference amplifier
Comparisons (according to reviewers)
- The Musical Fidelity may not sound quite as fluid, but it's a more direct presentation, a more present—explicit sonic signature
Takeaway: The Nu-Vista PAS amplifier is a well-built and powerful amplifier that delivers detailed and dynamic sound. Its robust design and revealing nature make it a great choice for audiophiles seeking a high-performance amplifier.
Video review
Our take on the brand
Integrated amplifiers have become the essential audio component, distilling sources, amp, preamp and interconnects into a single chassis. And since 2015, connoisseurs have revered the Gryphon Diablo 300 as the finest integrated amplifier ever produced and a genuine “Object of Desire.” Unanimously praised by critics and with thousands sold, it became High End Audio’s most coveted “Ultra-Luxe” integrated.
Our summary
Product Strengths
- Exceptional bass control, power, speed, and definition provides a bedrock foundation for the music
- Wide and deep soundstage with precise imaging
- Dead-neutral tonal balance with grain-free clarity, effortless speed, and precision
- Life-like dynamic expression and detail resolution, sounding exquisitely lifelike
- Lively, energetic sound combined with pleasing harmonics, warmth, and a kind of lusciousness achieves a nice balance
Product Considerations
- The binding posts are located low on the rear panel, which might be problematic for some installations
- It gets hot, requiring adequate ventilation
- It's a heavy unit, making it difficult to move and set up
- The cost is very high, making it exclusive-level hifi
- The speaker spiked feet can make it difficult to position the amplifier
Comparisons (according to reviewers)
- Vs Diablo 300, the Diablo 333 gives more music and musical information, developing the soundstage with harmonic information, knitting all the individual parts together; the music becomes less about individual things and more about the whole
- Strong resemblance to the Apex Commander combination, but at a fraction of the cost
- While the Antileon digs deeper and presents a fuller presentation across the low frequencies, the Diablo 333 slams harder and slightly tighter
Takeaway: The Gryphon Diablo 333 is a powerhouse integrated amplifier that combines exceptional power and control with refined sound and detailed musicality making it one of the very best amplifiers, be it integrated or not. Its versatility and musical soul make it a solid choice for anyone looking for an end-game component.
Video review
Our take on the brand
What competes at this price?
Our Summary
Product Strengths
- Combines a smooth, un-solid-state sound with loads of power and dynamics
- Has a practical and versatile design suitable for different placements
- Delivers a warm and involving sound
- Is a reviewer's 'favorite Krell ever' in part due to its relatively lighter weight—60 pounds—compared to older models
- Can be accessed via a web page that shows current operating temperature, fan speed, and overload conditions when wired to an Ethernet network
Product Considerations
- The top end is smooth and not very detailed, which may not appeal to audiophiles seeking highly detailed treble
- Despite iBias technology, the unit generates some wasted heat, indicated by the presence of cooling fans
- Some Krell enthusiasts may not like the lighter weight compared to older, heavier Krell amplifiers
Comparisons (according to reviewers)
- Vs Classé Audio CA-2300: The Solo 375 has better spaciousness, but the CA-2300 has more detailed and delicate treble
- Vs Pass Labs X350.5: The Solo 375 has smoother treble than the X350.5, but the X350.5 has greater spaciousness
Takeaway: The Solo 375 is a powerful amplifier that has a warm, smooth sound. It is versatile enough to be used in different setups, so it's a great choice for audiophiles.
Video review
Our take on the brand
Our Summary
Product Strengths
- Dual-mono design delivers 303W per channel into 8 ohms, providing power and control for any speaker
- High damping factor of over 4000 ensures absolute control over speaker drivers, resulting in pristine sound reproduction
- New DAC implementation based on ESS Sabre 9038Q2M chip offers pure audio fidelity without any resampling or upsampling
- Supports streaming via Apple AirPlay 2, Spotify Connect, Tidal Connect, and UPnP/DLNA
Product Considerations
- Does not have a phonostage
- Lacks an HDMI jack with ARC
- The supplied RC10 remote is slender with tiny buttons
- Weighs 22kg
- Minimalist design may be a bit bland for some
Comparisons (according to reviewers)
- Vs Bryston B135 SST 2, the H600 delivers more effortless presentation at high output
- Vs McIntosh MA9500, the H600 has bigger sound, is crisper and has higher resolution
Takeaway: The H600 is a versatile and powerful integrated amplifier that excels in delivering high-quality audio from both digital and analog sources. Its robust amplification makes it a great choice for audiophiles seeking a simplified yet high-end audio solution.
Video review
Our take on the brand
Our Summary
Product Strengths
- Offers a remarkably smooth, unforced, and natural presentation with a touch of warmth
- Excels in detail retrieval and textured presentation of instruments and vocals, making the music feel alive
- Presents a wide and holographic soundstage, especially when paired with speakers that are already strong in this area
- Demonstrates agility, precision, and clarity, combined with a naturalness that eluded earlier generations of Chord amplifiers
- Scales dynamically and has the ability to punch hard when required
Product Considerations
- Has a minimalist design with just four line-level inputs, lacking features like phono stages, tone controls, headphone outputs, or DAC modules
- Some may find its sonic signature prioritizes articulation over qualities such as richness and authority, potentially sounding thin if partnered poorly
- Balance control has no center indent or marked position
- The polychromatic lighting may be an issue for the color-blind
- Remote operation can be affected by direct sunlight
Comparisons (according to reviewers)
- Vs Rega Elex-R Mk3, the Chord Ultima Integrated delivers undeniably elevated sound in all respects, with greater dimensionality and smoother vocals
- Vs Bryston 7B 3 monoblocks, the Chord Ultima Integrated offers a weightier and more thunderous delivery, especially in the midrange and vocals, with more inner warmth in tone
- Vs Benchmark AHB2, the Chord Ultima Integrated provides a more energetic and fun listening experience, with Thor-like bass impact and overall superior dynamics
- Vs Accuphase E-270, the Chord Ultima Integrated is warmer, rounder, more powerful, and refined, with a more fluid and emotionally engaging performance
Takeaway: The Chord Ultima Integrated is a unique and well-built amplifier that combines a visually pleasing design with a captivating sound, full of detail and dynamic precision. It brings music to life with an engaging and immersive experience, making it a worthy addition to any audiophile's setup.
Video review
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Our Summary
Product Strengths
- Compact size, lightweight, and runs cool compared to traditional high-end amplifiers
- Exceptionally quiet operation, with reviewers noting a complete absence of hum or buzz
- Delivers a clean, crisp, and neutral sound signature without added coloration
- Upgradeable design, allowing users to update the amplifier with new GaN modules as technology evolves
- Produces a Single Ended Triode-like midrange and top end
Product Considerations
- The polished finish is a fingerprint magnet, requiring the use of gloves for handling
Comparisons (according to reviewers)
- Vs AGD Audion MKIII: The Duets offer a cleaner and more refined sound with improved bass and greater immediacy and snap compared to the Audion MKIII
- Vs Daniel Hertz Maria: The AGD Duets seem to have a little more inner resolution
- Vs Pass Labs X250.8: The AGD Duets performed to a higher level
- Vs Peachtree GaN 1/VTV GaN amps: AGD amps seem to be on another level in regards to design, and the sound is more refined and beautiful
- Vs Aavik U-150, Luxman 595, Yamaha A-S 3200, Axxess Forte 1, Line Magnetic 219ia: The AGD Duets performed to a higher level
Takeaway: The AGD Duet amplifiers offer a blend of cutting-edge technology, exceptional sound quality, and user-friendly design. They are a great option for those seeking a high-end audio experience in a compact and energy-efficient package.
Video review
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Our Summary
Product Strengths
- Known for combining the musicality of tube amplifiers with the precision and power of solid-state amplifiers.
- It provides a transparent sound with steel control, without the electronic 'shine' associated with transistor amplifiers.
- Exceptional bass performance, described as deep, explosive, and completely controlled.
- Homogeneous frequency range, offering a very high degree of transparency and control.
- Offers an ability to resolve even the finest musically significant details.
Product Considerations
- Requires a substantial amount of space due to its multi-component design.
- The sound offered might be 'too beautiful' for some listeners, as it is not 'brutal' or 'terse' enough.
- Requires care in using its switches to avoid shutdowns.
- Some reviewers note it was 'dark sounding' on the highs, though it did not lack information.
Comparisons (according to reviewers)
- Compared to Quad ESL loudspeakers, it surpasses the musicality and clarity achieved with many tube amps, rivaling even high-end options like Lamm Industries ML2.2 and Miyajima Laboratory 2010.
- The ASR has better bass and is more transparent than MBL, however, it lacks the grace that MBL offers.
- Compared to Rogue 180W monoblocks, the ASR Emitter II delivers better bass.
- The ASR Emitter II has slightly better bass control than Manley Neoclassic 500, but the Neoclassic 500 has a more marvelous style of fiddling.
- Compared to Edge and Audio Research, the ASR is darker sounding.
Takeaway: The ASR Emitter II Exclusive offers a combination of tube-like warmth and solid-state precision, making the listening experience a very involving one. It provides exceptional control and detail across the entire frequency range, making it a great choice for audiophiles.
Video review
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