VTL S-400: Elevating Audio Excellence



In the world of audio enthusiasts, the pursuit of high-quality sound amplification is a never-ending quest. Whether it’s for immersing ourselves in our favorite music or creating a cinematic experience in our home theaters, a powerful and reliable amplifier is essential. Today, we delve into the world of the VTL S-400 amplifier, a tube-based stereo power amplifier that promises to deliver an exceptional audio experience.

The VTL S-400 is part of the Reference series from the renowned American company, VTL. Drawing inspiration from their flagship monoblock amplifiers, the Siegfried, this stereo amplifier incorporates similar technical solutions while maintaining its own unique design and construction. With an impressive power output of 400 watts per channel at 4 Ohms (tetroid mode), or 200 watts per channel in triode mode, and 300 watts per channel at 8 Ohms (tetroid mode), or 150 watts per channel in triode mode, the VTL S-400 has the capability to handle any musical composition with ease.

But it’s not just about raw power; the VTL S-400 also excels in capturing the subtle nuances of a musical performance. By utilizing meticulously stabilized power sources and audiophile-grade components, this amplifier delivers fast, articulate sound reproduction while maintaining a rich and vibrant sonic character. The level of sonic saturation achieved by the VTL S-400 rivals that of its monoblock counterparts, such as the Siegfried.

In terms of aesthetics and functionality, the VTL S-400 inherits the luxurious appearance and user-friendly design from its monoblock sibling. It boasts several features that enhance convenience and ease of use. Automatic bias adjustment ensures optimal bias current without requiring manual adjustments. An intelligent fault-sensing system detects malfunctioning components and displays relevant information on the front panel display. Additionally, a built-in diagnostic system provides real-time monitoring of all operational parameters.

The VTL S-400’s impeccable build quality and thoughtful construction make it not only reliable but also a delight for even the most discerning audiophiles. It effortlessly reproduces intricate details and harmonics of musical compositions, resulting in a more lifelike and immersive listening experience. The amplifier’s ability to faithfully convey the complex tonalities of acoustic instruments without any hint of harshness or electronic sharpness is truly remarkable.

With its ability to combine the best qualities of various amplifier designs, including tube-based, transistor-based, single-ended triode, and push-pull configurations, the VTL S-400 sets new standards for stereo power amplifiers. Its substantial power reserves provide a solid foundation for musical reproduction, comparable to top-tier transistor amplifiers. The warmth, coherence, and richness of tonal textures are reminiscent of the best single-ended triode circuits. Furthermore, the S-400 effortlessly handles complex and dynamic passages, rivaling the performance of high-class push-pull amplifiers. The sound quality of the VTL S-400 comes remarkably close to that of its monoblock counterpart, the Siegfried, at a significantly lower price point.

In conclusion, the VTL S-400 is an exceptional stereo power amplifier that offers an unparalleled audio experience. With its powerful performance capabilities, meticulous construction, and refined sound characteristics, it is sure to satisfy even the most demanding music enthusiasts. Whether you’re looking to create a captivating home theater or seeking an immersive listening experience in your dedicated audio room, the VTL S-400 stands as a testament to VTL’s commitment to delivering superior sound quality.

Technical Specifications

The VTL S-400 amplifier is a powerful and versatile tube amplifier that offers impressive performance and audio quality. With its robust construction and advanced features, this amplifier is designed to meet the demands of even the most discerning audiophiles.

The amplifier boasts a power output of 400 watts per channel at 4 ohms in tetrode mode, and 200 watts per channel in triode mode. At 8 ohms, it delivers 300 watts in tetrode mode and 150 watts in triode mode. This ample power ensures that the amplifier can effortlessly drive any type of speakers, allowing for a dynamic and immersive listening experience.

In terms of sound quality, the VTL S-400 excels with its high signal-to-noise ratio (SNR) of 90 dB, which means that the amplifier effectively minimizes background noise and delivers a clean and clear audio signal. Additionally, the total harmonic distortion (THD) is kept at a low level, ensuring that the sound reproduction remains faithful to the original recording.

The amplifier offers a range of inputs and outputs to accommodate various audio sources. It features balanced inputs for enhanced audio performance and noise rejection. The absence of XLR inputs and outputs may limit connectivity options for some users. However, it compensates for this with its RCA line-level inputs and outputs.

With a frequency response ranging from 20 Hz to 20 kHz, the VTL S-400 covers the entire audible spectrum, reproducing both low and high frequencies with precision and accuracy. It is compatible with a wide range of audio formats, allowing you to enjoy your favorite music in various formats without compromising on sound quality.

The amplifier is designed to work with speakers of different impedance levels. While it does not support multiple speaker pairs or separate terminals for different impedance levels, it can handle a wide range of speaker impedances effectively.

Overall, the VTL S-400 impresses with its technical specifications, offering ample power, low distortion, and a wide frequency response. While it may not have all the connectivity options of some other amplifiers, its performance and sound quality make it a compelling choice for audiophiles seeking a powerful and reliable tube amplifier.

Design and Construction

The VTL S-400 amplifier boasts a sleek and elegant design that is sure to catch the eye of any audio enthusiast. Its silver color adds a touch of sophistication to any audio setup. The amplifier is constructed using high-quality materials, ensuring durability and longevity.

One notable design feature of the VTL S-400 is its efficient cooling system. The amplifier is designed with ventilation slots and strategically placed heat sinks to dissipate heat effectively, preventing overheating and ensuring optimal performance even during long listening sessions.

In terms of reduced interference, the VTL S-400 incorporates shielding and isolation techniques to minimize external noise and electromagnetic interference. This results in a cleaner and more accurate sound reproduction.

The connectors and switches on the VTL S-400 are of exceptional quality. They are sturdy and provide a secure connection, ensuring reliable signal transmission. The switches have a satisfying tactile feel, indicating their durability and attention to detail in the construction process.

Overall, the design and construction of the VTL S-400 amplifier showcase both aesthetics and functionality. Its sleek appearance, high-quality materials, efficient cooling system, and reliable connectors make it a standout choice for audio enthusiasts looking for both style and performance in their audio equipment.


The VTL S-400 amplifier offers a wide range of functionality, making it versatile and compatible with various audio sources. Whether you want to connect your CD player, computer, smartphone, or any other audio device, this amplifier has you covered.

With its multiple inputs and outputs, the VTL S-400 allows for easy connectivity and integration into your existing audio setup. It provides both RCA and XLR inputs, ensuring compatibility with a wide range of audio sources. This means you can easily connect your favorite CD player or even stream music from your computer or smartphone.

In terms of controls, the VTL S-400 offers a comprehensive set of options. While it does not have balance controls or tone adjustments, it does provide a mode switch on the front panel that allows you to toggle between triode and pentode modes. This feature enables you to fine-tune the sound according to your preferences and the characteristics of your speakers.

Additionally, the amplifier incorporates an intelligent fault-sensing system that detects any issues with the tubes or power supply. It displays warnings on the front panel in case of voltage fluctuations or if any of the tubes need replacement. This ensures that you can maintain optimal performance without worrying about potential problems.

Overall, the functionality of the VTL S-400 is designed to provide convenience and flexibility in operation. It offers various connectivity options for different audio sources and incorporates useful features such as mode switches and fault-sensing systems to enhance user experience.

Sound Characteristics

The VTL S-400 amplifier delivers exceptional sound characteristics that will impress even the most discerning audiophiles. With its powerful output and attention to detail, this amplifier truly shines in its ability to reproduce music with precision and clarity.

One of the standout features of the VTL S-400 is its ability to provide an immersive listening experience with excellent instrument separation. Each instrument is distinct and well-defined, allowing the listener to fully appreciate the nuances of the music. The amplifier’s ability to accurately reproduce details adds depth and realism to the soundstage, making you feel like you’re right there in the recording studio.

The bass response of the VTL S-400 is nothing short of impressive. It delivers deep, tight, and controlled bass that adds a solid foundation to any music genre. Whether you’re listening to rock, jazz, or classical music, the amplifier ensures that the low-end frequencies are reproduced accurately and with authority.

In terms of treble clarity, the VTL S-400 excels at providing a smooth and detailed high-frequency response. The highs are crisp, clear, and never harsh or fatiguing. This allows for an enjoyable listening experience without any sibilance or distortion.

When it comes to overall sound presentation, the VTL S-400 offers a balanced and natural sound signature. It brings out the best in every music genre, allowing you to appreciate the unique characteristics of each recording. Whether you’re listening to delicate acoustic tracks or dynamic orchestral performances, this amplifier faithfully reproduces the intended sound with accuracy and finesse.

The VTL S-400 has a remarkable impact on various music genres. It effortlessly handles complex passages in classical compositions with grace and precision. The amplifier captures every nuance of vocals in jazz recordings, bringing out their warmth and emotion. In rock and electronic genres, it provides a powerful and energetic performance that will have you tapping your feet and feeling fully immersed in the music.

Overall, the sound characteristics of the VTL S-400 are nothing short of exceptional. Its ability to reproduce music with accuracy, detail, and depth makes it a top choice for audio enthusiasts who value high-quality sound reproduction. Whether you’re a casual listener or a dedicated audiophile, this amplifier will elevate your listening experience to new heights.

Sound Performance

The sound performance of the VTL S-400 amplifier is truly exceptional, captivating listeners with its ability to faithfully reproduce audio signals. From the moment you press play, this amplifier transports you into a world of sonic bliss.

One of the standout qualities of the VTL S-400 is its remarkable clarity. Every note, every instrument, and every vocal is rendered with stunning precision and detail. The amplifier effortlessly unveils the subtle nuances and intricacies of the music, allowing you to hear even the tiniest details that might have been previously hidden. It brings a new level of transparency to your listening experience, making you feel like you are right there in the recording studio.

Furthermore, the dynamics of the VTL S-400 are truly impressive. It effortlessly handles both delicate passages and explosive crescendos with finesse and control. The amplifier has an uncanny ability to bring music to life, capturing the full range of emotions conveyed by the artist. Whether it’s a soft whisper or a thunderous drumbeat, the VTL S-400 ensures that each moment is delivered with impact and intensity.

In terms of tonal balance, the VTL S-400 excels across the entire frequency range. The lows are deep and powerful, providing a solid foundation for bass-heavy tracks. The midrange is lush and rich, allowing vocals and instruments to shine with warmth and presence. The highs are detailed and extended, adding sparkle and airiness to the overall sound signature. The amplifier strikes a perfect balance between these frequency ranges, creating a cohesive and harmonious soundstage that is both engaging and immersive.

Whether you’re listening to classical symphonies, rock anthems, or jazz improvisations, the VTL S-400 delivers an audio performance that is nothing short of breathtaking. Its ability to faithfully reproduce music with clarity, dynamics, and tonal balance sets it apart from other amplifiers in its class.

In conclusion, the sound performance of the VTL S-400 is truly remarkable. It brings music to life in a way that is both captivating and emotionally engaging. With its exceptional clarity, impressive dynamics, and impeccable tonal balance, this amplifier is a true gem for any audiophile seeking an unparalleled listening experience.


The VTL S-400 amplifier offers several advantages that set it apart from its competitors in the market. Firstly, its power output of 400 watts per channel on 4 ohms (tetroid) and 200 watts per channel on 4 ohms (triode), and 300 watts per channel on 8 ohms (tetroid) and 150 watts per channel on 8 ohms (triode) is impressive and ensures that it can effortlessly handle any type of music and drive even the most demanding speakers.

Another advantage of the VTL S-400 is its exceptional sound quality. Thanks to its high-quality components and audio-grade circuitry, it delivers a fast, articulate, and incredibly immersive sound experience. The amplifier is capable of reproducing even the finest nuances of a musical composition, allowing the listener to truly appreciate the intricacies and details in the music.

Additionally, the VTL S-400 features a range of convenient functions that enhance user experience. The automatic bias adjustment ensures that the amplifier always maintains optimal bias levels without the need for manual adjustments. The built-in diagnostic system provides real-time information about any faults or issues, making it easier for users to identify and resolve problems. The RS-232 interface allows for remote control and integration into smart home systems, providing users with easy access to amplifier status and diagnostics.

When compared to other amplifiers in its price range, the VTL S-400 offers exceptional value for money. It delivers sound quality that rivals top-tier monoblock amplifiers like the Siegfried, but at a significantly lower price point. This makes it an attractive option for audiophiles who want high-end performance without breaking the bank.

In conclusion, the VTL S-400 amplifier stands out with its impressive power output, exceptional sound quality, convenient features, and competitive pricing. It offers a combination of performance and value that is hard to find in other amplifiers in the market. Whether you are a music enthusiast or a professional audio engineer, the VTL S-400 is a reliable and high-performing amplifier that will elevate your listening experience to new heights.

Value for Money

The VTL S-400 amplifier offers exceptional value for money, delivering a combination of high-performance audio, impressive features, and a reasonable price point. With its powerful output of 400 watts per channel on 4 ohms (tetroid) and 200 watts per channel on 4 ohms (triode), or 300 watts per channel on 8 ohms (tetroid) and 150 watts per channel on 8 ohms (triode), this amplifier provides ample power to drive any type of speaker system.

In addition to its impressive power capabilities, the VTL S-400 also boasts a range of convenient features that enhance its value. The automatic bias adjustment ensures optimal performance without the need for manual adjustments, while the built-in fault detection system alerts users to any issues that may arise. The integrated diagnostic system allows for easy monitoring and control, providing peace of mind to users.

Considering its technical specifications, design quality, and functionality, the VTL S-400 offers excellent value for money compared to other amplifiers in its class. It combines the performance and features typically found in top-tier amplifiers at a more affordable price point. This makes it an attractive option for both audiophiles seeking high-quality sound reproduction and budget-conscious consumers looking for a reliable and powerful amplifier without breaking the bank.

Overall, the VTL S-400 provides exceptional value for money with its impressive performance capabilities, advanced features, and reasonable price. It sets a new standard for stereo power amplifiers in terms of both audio quality and affordability. Whether you are a discerning music lover or simply looking to upgrade your audio setup, the VTL S-400 offers an excellent balance between performance and cost-effectiveness.


In conclusion, the VTL S-400 amplifier from the Reference Series is a remarkable piece of audio equipment that delivers exceptional performance and versatility. With its impressive power output of 400 watts per channel, this amplifier is capable of handling any type of music and driving any speakers with ease.

The design and construction of the VTL S-400 are top-notch, showcasing a sleek and luxurious appearance that is both visually appealing and functional. The inclusion of features such as automatic bias adjustment, fault sensing, and built-in diagnostics adds convenience and ensures optimal performance at all times.

When it comes to sound characteristics, the VTL S-400 truly shines. It effortlessly reproduces even the most delicate nuances in music, allowing for a truly immersive listening experience. The sound is fast, articulate, and richly detailed, reminiscent of the performance delivered by the flagship monoblock amplifiers Siegfried.

One of the major advantages of the VTL S-400 is its ability to combine the best qualities of different amplifier designs. Its immense power reserves provide a solid foundation for musical reproduction, akin to high-end transistor amplifiers. At the same time, it exhibits warmth, coherence, and tonal richness similar to triode single-ended circuits. Additionally, it handles complex dynamic passages with ease, rivaling top-class push-pull amplifiers.

Considering its exceptional sound quality and performance that comes close to that of the Siegfried at a significantly lower price point, the VTL S-400 offers great value for money. It sets new standards for stereo power amplifiers and will surely satisfy even the most discerning audiophiles.

For potential buyers looking for an amplifier that combines power, precision, and musicality in one package, the VTL S-400 is an excellent choice. Whether you have demanding speakers or simply desire an immersive listening experience with fine details and accurate reproduction of instruments’ timbre, this amplifier will exceed your expectations.

In conclusion, the VTL S-400 amplifier is a true masterpiece in the world of high-end audio. Its combination of power, versatility, and exceptional sound quality make it a worthy investment for any serious music lover. With its impressive performance and value for money, the VTL S-400 is highly recommended for those seeking an amplifier that delivers both power and finesse.

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