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.
All
SPA IV Apollo
reviews
Manufacturer details
- Input Sensitivity: 1V
- Input Impedance: 47K or 100K Ohms
- Output Impedance: 4 & 8 Ohms
- Max Power Consumption: 250W
- Output Noise, Unweighted: < 0.5 mVrms
- Dimensions (without tubes and feet): 250mm x 440mm x 400mm (Height x Width x Depth)
- Weight: 35kg
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:
- SW1X uses classic circuit designs, often inspired by Kondo and Audio Note UK, reimagined with modern enhancements and a focus on harmonically matched components.
- A key element is the use of non-oversampling (NOS) DACs and a lack of digital filters, aiming to eliminate digital artifacts and achieve a more analog-like sound reproduction.
- SW1X offers a wide range of models and versions within each product line, allowing customers to tailor the sound to their specific tastes and system synergy through component and material choices, such as copper or silver wiring and different capacitor types.
Select products
SW1X DAC I Special 2
- Positioning: Entry-level line, designed for affordability and compactness.
- Description: Offers a pure NOS R2R design, providing a musical and organic sound that is rare in its price range. It features a simple yet effective valve amplification topology. Compared to higher models like the DAC II, it lacks the more advanced power supply and output stage configurations, making it suitable for smaller setups and those with a limited budget.
SW1X DAC II Balanced Special
- Positioning: Mid-range model with enhanced features for balanced audio output.
- Description: Combines the digital side of the DAC II with the power tube output stage of the DAC IV, offering a dynamic and engaging sound. It features a balanced signal output transformer and active I/V conversion, providing a more refined audio experience than the DAC I.
SW1X DAC III VSB
- Positioning: Mid to high-end model with USB connectivity for versatile use.
- Description: Integrates a USB interface, making it versatile for modern digital setups. It offers a pure NOS design with a valve output stage, providing a rich and detailed sound. Compared to the DAC II, it includes larger power supplies and a more robust output stage.
SW1X DAC IV
- Positioning: High-end model with advanced power supply and output stage.
- Description: Features directly heated diodes and a power valve output stage, offering a mature and large-scale sonic presentation. It surpasses the DAC III in dynamic range and musical refinement.
SW1X DAC X
- Positioning: Flagship model, representing the pinnacle of SW1X engineering.
- Description: The ultimate endgame DAC, combining technologies from the entire SW1X lineup into one chassis. It features a non-oversampling R2R design with a directly heated power triode valve output stage, delivering a musical and natural sound.
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SW1X
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Product Strengths
- Harmonic content is reproduced beyond what the reviewer had heard before, making instruments and voices sound more fully formed
- Creates a dimensional physicality with full voice, turning recorded events into a real-life experience
- Fast and resolving without being harsh, and presents music with a high degree of tonal saturation without feeling slow
- Reveals nuance in recordings, making small details easier to distinguish
- Achieves a balance that makes components worth the money, provides realistic experience regardless of the program material
Product Considerations
- The single-ended input was found to sound slightly more immediate than the balanced XLR input, though the difference was minor
- Requires about 90 minutes to fully warm up and stabilize for optimal performance
Comparisons (according to reviewers)
- The Riviera amplifiers have slightly more tonal saturation than the Pass Labs XA 25
- The separates (APL10 and AFM25) are more quietly seductive and take more time and attention to fully appreciate, compared to the Riviera Labs Levante integrated amplifier
Takeaway: The AFM25 monoblocks offer a unique and captivating sound that expands the enjoyment and connection to music. When paired with efficient speakers, they provide a realistic and detailed listening experience that makes the music feel more alive.
Video review
Our take on the brand
Our summary
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
Our take on the brand
What competes at this price?
Our Summary
Product Strengths
- Highly customizable, allowing users to request specific configurations and tube types
- Offers a wide range of tube rolling options to pinpoint the desired sound signature
- Price-to-performance ratio is excellent, competing with amps costing around $5,000
- Can drive high impedance headphones like ZMF, HD 800, and T1, as well as planars and low ohm headphones with specific tube configurations
- Can sound very good with inexpensive tubes, but can be elevated to a ridiculous performance level with higher end tubes
- There is a HeadFi thread to help with connectivity options
Product Considerations
- Ordering process is unconventional, requiring direct communication through a HeadFi thread
- There is a wait time for builds, potentially around six months
- Tube rolling can become expensive due to the variety of options and the cost of some tubes
Takeaway: The Glenn is a highly customizable amplifier that provides excellent performance for the price, especially for those who enjoy tube rolling and experimenting with different sound signatures. It is a versatile amp that can drive a wide range of headphones, making it a great choice for many audiophiles.
Video review
Our take on the brand
Our Summary
Product Strengths
- Alluring and sophisticated midrange with a tonal and textural directness
- Class-leading differentiation of dynamics and tonalities between instruments
- Engineering feat so thorough in forging a signal path of the purest as to be fanatical
- Brings a whole new level of sophistication to the art of music reproduction
- Exerts complete control of speakers with high sensitivity
Product Considerations
- The RCA jacks are closely spaced, necessitating the use of thin interconnects
- Eight watts may not be enough for speakers with lower sensitivity in larger rooms, potentially leading to dynamic compression and distortion
- Low output limits the range of suitable speakers compared to solid-state amplifiers
Takeaway: The SW1X AMP V 'Titan' Special is a handcrafted, ultra hifi amplifier from the United Kingdom, offering definitive performance, beauty of sound, and functional options. It stands apart in the field of the most exalted directly-heated triode amplifications, especially when paired with high-efficiency speakers.
Video review
Our take on the brand
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
Our take on the brand
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
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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