Review: Lab 12 Integre4 MK2 Tube Integrated Amplifier

Review: Lab 12 Integre4 MK2 Tube Integrated Amplifier - The Lab 12 Integre4 MK2 Amplifier is a high-end audio masterpiece known for its versatile sound and meticulous craftsmanship.


In the realm of high-end audio equipment, where digital precision and analog warmth often converge, the Lab 12 Integre4 MK2 integrated amplifier stands as a fascinating testament to the harmony of these two worlds. This audio marvel is a creation of CM-Audio, renowned for its digital expertise and acclaimed as the “Digital Audio Competence Center.” However, this amplifier takes a bold leap into the analog domain, embracing tube amplification’s rich, classic sound. With a price tag of 5,640 euros, the Lab 12 Integre4 MK2 is more than just a musical device; it’s a carefully crafted piece of engineering that marries traditional tube technology with modern design and functionality.

The story behind the Lab 12 Integre4 MK2’s journey from a digital specialist’s world to the realm of tubes is captivating. It all began with a chance encounter between CM-Audio and Lab 12, catalyzed by a mutual acquaintance in the audio industry. The Lab 12 brand, forged by Stratos Vichos, an electrical engineer turned hi-fi enthusiast, is a testament to passion and dedication. His journey, born out of adversity during the Greek economic crisis, led to the creation of Lab 12, a brand now celebrated worldwide with a network of over 27 distributors. In this review, we delve into the intricacies of the Lab 12 Integre4 MK2, exploring its design, performance, and the unique blend of digital precision and analog charm that makes it an intriguing addition to high-end audio.


  • Model: Lab 12 Integre4 MK2
  • Concept: tube integrated amplifier
  • Price: 5,640 euros (from January 1st, 2023: 5,930 euros)
  • Tubes: 4 x 6n1p dual triodes, 4 x KT170 pentodes
  • Dimensions and weight: 430 x 190 x 290 mm (WxHxD); 22kg
  • Inputs: 5 x high level (4 x RCA, 1 x RCA or XLR)
  • Outputs: speaker terminals for a pair of speakers, 6.3 mm jack
  • Output power: 2 x 75 watts
  • Other: remote control, quiescent current adjustable, compatible with EL34, 6550, KT88, KT120, KT150, KT170
  • Warranty: 5 years (tubes: 6 months)

The Story Behind Lab 12

CM-Audio’s Markus Flöter shares how they connected with Lab 12. It began through a dealer friend, Jürgen Gruner, from “Heimstatt der Musik” in Frechen, where they discovered Lab 12’s commitment to quality components, meticulous circuit board layout, excellent assembly, and exceptional sound. Lab 12’s founder, Stratos Vichos, originally an electrical engineer, turned to hi-fi development after losing his job during the Greek economic crisis. The name “Lab 12” is a nod to the garage where it all started, and today, Lab 12’s reputation has spread worldwide with over 27 distributors.

Design and Build Quality

The Lab 12 Integre4 MK2 makes a striking first impression with its meticulously designed exterior. Crafted with both aesthetics and functionality in mind, it is a testament to the manufacturer’s commitment to excellence. The chassis of the amplifier is constructed from robust sheet steel, ensuring durability and stability. Its front panel, a 5-millimeter thick aluminum plate, exudes a sense of premium quality. Available in either silver or black, this front panel features a large, easy-to-read OLED display at its center. Even in direct sunlight, the display remains highly legible, providing essential information about the selected input and menu options. Such attention to detail extends throughout the amplifier’s design, where no element feels overlooked.

Beyond aesthetics, Lab 12 has ingeniously incorporated noise-reduction features into the amplifier’s chassis. With an aim to reduce interference and distortion, particularly in the audio signal path, the “noise reduction chassis” remains a well-guarded secret in terms of its precise engineering. This commitment to minimizing external influences showcases Lab 12’s dedication to delivering pristine sound quality. Furthermore, the overall build quality of the Lab 12 Integre4 MK2 is nothing short of exceptional. Every component is meticulously assembled, and the amplifier exhibits a level of sturdiness that ensures nothing wobbles or rattles. Such precision in construction not only enhances its aesthetic appeal but also contributes to its overall performance and longevity.

In conclusion, the Lab 12 Integre4 MK2 is a true marriage of form and functionality. Its design exudes elegance and sophistication, with a thoughtful combination of premium materials, a user-friendly OLED display, and an emphasis on reducing unwanted interference. This amplifier’s build quality, characterized by meticulous assembly and robust construction, guarantees long-lasting reliability. It is a high-end audio component that not only sounds excellent but also complements any audio setup with its striking design and exceptional craftsmanship.

User-Friendly Operation

One of the standout features of the Lab 12 Integre4 MK2 is its user-friendly operation, designed to provide a seamless and enjoyable experience for audio enthusiasts. Lab 12 has made sure that users can effortlessly navigate the amplifier’s functions, making it accessible to both novices and seasoned audiophiles.

The centerpiece of the user interface is the easy-grip controller made of solid aluminum, which includes a push-turn knob on the front panel. This controller operates smoothly, offering users a satisfying tactile feel and a clearly defined pressure point for selecting menu items. The intuitive design ensures that adjusting settings and preferences becomes an intuitive process. Additionally, the included remote control extends the convenience of operation, allowing users to manage the amplifier’s functions from a distance, which is particularly useful when fine-tuning audio settings during playback.

One unique feature that sets the Lab 12 Integre4 MK2 apart is its tube running time display. This innovative feature shows users the number of hours each tube has been in use. It not only provides valuable information about the tubes’ lifespan but also adds an element of interactivity and engagement for enthusiasts who want to keep a close eye on the amplifier’s performance. Moreover, users can easily adjust the tube bias using four small rotary controls located on the front panel. The amplifier’s OLED display provides precise information about the quiescent current, ensuring that users can optimize the bias for their preferred tubes accurately. This level of control and transparency demonstrates Lab 12’s commitment to empowering users to customize their listening experience.

In conclusion, the Lab 12 Integre4 MK2 stands out for its user-friendly operation, designed to cater to both newcomers and seasoned audiophiles. The combination of a tactile, well-designed controller on the front panel and a convenient remote control ensures effortless navigation and control. The tube running time display and bias adjustment options provide a unique level of interactivity, making it an engaging experience for enthusiasts. Lab 12’s commitment to user convenience and customization is evident in every aspect of the amplifier’s operation, making it a joy to use and fine-tune for optimal audio performance.

Connectivity and Tube Options

One of the remarkable features of the Lab 12 Integre4 MK2 is its tube options, providing users with the ability to tailor the amplifier’s sound performance to their preferences. Out of the box, the Integre4 MK2 comes equipped with four KT170 power pentodes, along with four 6n1p dual triodes. This combination delivers a powerful and dynamic audio experience, suitable for a wide range of music genres and listening preferences. However, Lab 12 goes a step further by allowing users to customize the tubes by placing them in the ceramic bases themselves, a process that many enthusiasts find enjoyable and satisfying. This hands-on approach ensures that users have a direct influence on the amplifier’s sound characteristics.

Moreover, the Lab 12 Integre4 MK2 is compatible with various power amplifier tubes, including the EL34, 6550, KT88, KT120, and KT150. This versatility empowers users to experiment with different tubes, exploring their unique sonic signatures and fine-tuning the amplifier to match their preferred audio profile. Lab 12’s commitment to tube options highlights their dedication to providing users with a customizable and adaptable amplifier that can evolve with changing audio preferences and equipment upgrades. Whether users seek the warmth of classic tube sound or the precision of modern audio reproduction, the Integre4 MK2’s tube options make it a compelling choice for those who value sonic customization and flexibility.

Technical Advancements

The Lab 12 Integre4 MK2 incorporates several noteworthy technical advancements that elevate its performance and set it apart in the world of integrated tube amplifiers.

  • Double-Mono Topology: Lab 12 introduces a newly designed “100 percent double-mono topology” in the Integre4 MK2. This design separates the power supplies for each channel entirely, ensuring that each channel operates independently without any crosstalk or interference. This approach, combined with meticulous engineering, results in an amplifier that delivers exceptional stereo imaging and channel separation, providing audiophiles with a more immersive and accurate listening experience.
  • Separate Rails Separate Ground (SRSG): The use of “SRSG” technology in the Integre4 MK2 further enhances its performance. SRSG stands for “Separate Rails Separate Ground,” a design philosophy that keeps power and ground paths for each channel entirely separate from audio signal paths. This separation minimizes the risk of noise interference, ensuring that the audio signal remains pristine from input to output. It’s a crucial advancement for maintaining audio purity, especially when dealing with delicate tube amplification.
  • Improved Output Transformers: Lab 12 has also upgraded the output transformers in the Integre4 MK2. Rather than using off-the-shelf parts, they employ custom-made transformers produced exclusively to Lab 12’s specifications. These transformers play a critical role in shaping the amplifier’s sound signature. The improved design enhances the amplifier’s efficiency and ensures that it can deliver the desired power and fidelity to your speakers, contributing to a more transparent and detailed soundstage.
  • Zero Negative Feedback: Similar to its predecessor, the Integre4 MK2 retains a design that avoids the use of global negative feedback throughout the amplifier’s circuitry. This approach prioritizes sonic purity and transparency over certain types of distortion control. While it may lead to a slightly different sonic signature compared to amplifiers with feedback loops, it appeals to audiophiles who prioritize a more natural and uncolored sound reproduction.

These technical advancements underscore Lab 12’s dedication to pushing the boundaries of what integrated tube amplifiers can achieve. By combining innovative design principles, meticulous engineering, and high-quality components, the Integre4 MK2 represents a significant step forward in delivering exceptional audio performance to discerning listeners. These advancements ensure that the amplifier produces captivating sound and maintains the highest standards of quality and reliability, making it a valuable addition to any audio system.

Listening Experience and Comparisons

The Lab 12 Integre4 MK2 delivers a distinctive listening experience. It excels with music that benefits from its powerful bass, dynamic speed, and direct approach. The amplifier shines with clearly orchestrated music, offering precise instrument placement, and a three-dimensional soundstage. It places voices and mid-range instruments forward, providing an intense and intimate experience. However, at high volumes and with complex music, it can be slightly fatiguing, especially with transparent or presence-emphasized speakers. The treble is transparent and never obtrusive, offering a finely detailed sound.

Sound Quality: An Audiophile’s Delight

The Lab 12 Integre4 MK2 is more than just a beautifully designed piece of audio equipment; it’s a powerhouse that delivers an audiophile-grade sound quality that can enthrall even the most discerning listeners. Its sound signature is characterized by a combination of qualities that make it a unique and captivating addition to any high-end audio setup.

  • Bass Authority: One of the standout features of the Integre4 MK2 is its commanding bass performance. With an emphasis on the lower frequencies, it reproduces deep, impactful bass notes with a level of authority that can be felt as much as it is heard. When tasked with tracks featuring challenging basslines, such as Massive Attack’s “Unfinished Sympathy,” this amplifier delivers a visceral experience that fills the room with energy. The substantial bass presence sets it apart from other amplifiers, making it an excellent choice for music genres that demand a strong and controlled low end.
  • Dynamic Prowess: The Integre4 MK2’s dynamic capabilities are nothing short of impressive. It effortlessly handles large level jumps with remarkable speed and precision, making it a dynamic powerhouse. This characteristic is particularly noticeable with tracks that feature sudden shifts in volume, such as Brendan Perry’s “This Boy” from the album “Ark.” The amplifier’s ability to convey the dynamic nuances of the music allows listeners to experience the full emotional impact of their favorite tracks, whether it’s the punch of a bass drum or the subtleties of a saxophone solo.
  • Midrange Clarity: While the Integre4 MK2 exhibits a powerful bass and dynamic prowess, it also excels in delivering a clear and transparent midrange. Male and female vocals, as well as midrange instruments like strings and saxophones, are presented with remarkable clarity and precision. The amplifier’s direct and intense response in the midrange brings performers to the forefront of the soundstage, creating an intimate and emotionally charged listening experience. This quality is especially appealing for genres like jazz, acoustic music, and vocal-driven tracks, where the accuracy and authenticity of the midrange performance can make or break the listening experience.
  • Treble Precision: The Integre4 MK2’s approach to high frequencies is characterized by precision and control. It reproduces frequencies above 2500 Hertz with clarity and accuracy, ensuring that treble elements, such as cymbals and high-pitched instruments, are presented with sharpness and definition. Even at high volumes, the amplifier maintains a linear and non-fatiguing treble response, avoiding harshness or sibilance. This level of treble precision adds an extra layer of detail to the music and contributes to a more realistic and engaging listening experience.
  • Three-Dimensional Soundstage: The amplifier’s spatial representation is noteworthy, particularly when it comes to the placement and separation of instruments and vocals within the soundstage. It excels in creating a three-dimensional sonic landscape where each element occupies a distinct and well-defined position. Male vocals, such as those of Jarvis Cocker or Benjamin Clementine, are positioned prominently in front of the listener, while instrumental details extend both in front and behind the speakers. This immersive soundstage enhances the sense of realism and allows listeners to feel as though they are in the presence of the performers.

Sound Test and Comparisons:

During rigorous sound testing, the Lab 12 Integre4 MK2 demonstrated its prowess across various musical genres and with different speakers, showcasing its versatility and audiophile-grade performance.

  • Massive Attack’s “Unfinished Sympathy”: This classic track from “Blue Lines” served as an excellent test for the amplifier’s bass authority. The Integre4 MK2 delivered an unmistakable sense of power and depth in the bass frequencies that outperformed many other amplifiers. The basslines in this track resonated with energy and impact that were truly impressive.
  • Brendan Perry’s “This Boy” (from “Ark”): The dynamic capabilities of the amplifier shone through in this track, capturing the sudden level jumps and intricate details with effortless speed. The bass drum and saxophones were rendered with precision and emotional intensity, highlighting the amplifier’s ability to convey the dynamic nuances of the music.
  • Jarvis Cocker, Benjamin Clementine, and Brendan Perry: Male vocals in tracks from artists like Jarvis Cocker, Benjamin Clementine, and Brendan Perry were particularly revealing of the amplifier’s midrange clarity. The direct and intense presentation of these vocals created an intimate and emotionally charged listening experience, allowing listeners to connect deeply with the performers.
  • Treble Precision and Detail: Tracks featuring cymbals and high-pitched instruments, such as Erika de Casier’s “Polite,” showcased the amplifier’s treble precision and detail. The sharp and well-defined treble response added an extra layer of texture and realism to the music.
  • Three-Dimensional Soundstage: The Integre4 MK2 consistently impressed with its ability to create a three-dimensional soundstage. It excelled in placing vocals and instruments with precision and depth, enhancing the overall listening experience. Tracks like Yello’s “Toy” and Micah Frank & Chet Doxas’ “The Music of Hildegard von Bingen” benefitted greatly from the amplifier’s spatial representation.

In summary, the Lab 12 Integre4 MK2 is a tube amplifier that combines powerful bass, dynamic prowess, midrange clarity, treble precision, and an immersive three-dimensional soundstage to deliver an audiophile’s delight. Its performance across various genres and its ability to excel with different speakers make it a versatile and compelling choice for discerning music enthusiasts seeking an exceptional listening experience.

Reasons to Buy the Lab 12 Integre4 MK2 Amplifier:

  1. Audiophile-Grade Sound: If you’re passionate about high-quality sound and want an amplifier that can deliver a captivating audio experience, the Integre4 MK2 is a compelling choice. Its combination of powerful bass, dynamic prowess, midrange clarity, and treble precision makes it an audiophile’s delight.
  2. Versatile Performance: Whether you enjoy a wide range of music genres or prefer specific types of music, this amplifier can handle it all. It excels with everything from rock and electronic to jazz and classical, making it versatile for various listening preferences.
  3. Immersive Soundstage: The three-dimensional soundstage created by the Integre4 MK2 adds depth and realism to your music. It places vocals and instruments with precision, immersing you in the music and enhancing your overall listening experience.
  4. Quality Build and Design: With its sturdy sheet steel chassis, high-quality components, and meticulous craftsmanship, the Integre4 MK2 boasts an impressive build quality. Its sleek aluminum front panel and large OLED display add a touch of elegance to your audio setup.
  5. Tube Options: The ability to use a variety of power amplifier tubes, including EL34, 6550, KT88, KT120, and KT150, allows you to customize the amplifier’s sound to your liking. This flexibility is a significant advantage for tube enthusiasts.

Reasons to Consider Other Options:

  1. Budget Constraints: The Integre4 MK2 is a premium amplifier with a price tag to match its high-end performance. If you have a limited budget, you may need to explore more affordable amplification options.
  2. Preference for Transistor Sound: While the Integre4 MK2 offers a unique tube sound signature, some listeners prefer the characteristics of solid-state amplifiers. If you lean more towards a transistor-based sound, you might want to explore alternatives.
  3. Space Constraints: This amplifier is substantial both in terms of performance and physical size. If you have limited space in your audio setup, you may need to consider smaller amplifier options.
  4. Simplified Features: The Integre4 MK2 is designed primarily for audiophiles who appreciate advanced features and customization. If you prefer a more straightforward amplifier without extensive controls and options, you might find this model overwhelming.

In summary, the Lab 12 Integre4 MK2 amplifier is an exceptional choice for audiophiles seeking top-tier sound quality and a versatile listening experience. However, it may not be the best fit for those on a tight budget or individuals who prefer the characteristics of solid-state amplifiers. Ultimately, your decision should align with your specific audio preferences and requirements.

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The Lab 12 Integre4 MK2 is a character-enhancing amplifier, impressing with its dynamic energy and direct approach. It excels with clearly orchestrated music, offering exceptional instrument placement and three-dimensional sound. While it may not be entirely linear, its tuning is skillful and enjoyable, providing a unique listening experience. It pairs well with speakers that complement its character, making it a great choice for those seeking a fun and engaging tube amplifier. With solid build quality, versatile connectivity, and an affordable price point, the Lab 12 Integre4 MK2 is a compelling option for tube enthusiasts.

Advantages of the Lab 12 Integre4 MK2 Amplifier:

  1. High-Quality Sound: The amplifier delivers exceptional sound quality with powerful bass, dynamic range, and a clear midrange, making it ideal for audiophiles seeking an immersive listening experience.
  2. Versatility: It performs well across various music genres, making it suitable for diverse musical preferences.
  3. Customizable Tube Options: Using various power amplifier tubes allows users to fine-tune the amplifier’s sound signature to their liking, providing flexibility and personalization.
  4. Quality Build: The amplifier is built with meticulous attention to detail, featuring a sturdy steel chassis, high-quality components, and an elegant aluminum front panel.
  5. Three-Dimensional Soundstage: The Integre4 MK2 creates a captivating and precise three-dimensional soundstage, enhancing the spatial placement of instruments and vocals.

Disadvantages of the Lab 12 Integre4 MK2 Amplifier:

  1. High Price: Its premium price tag may be prohibitive for budget-conscious consumers, limiting its accessibility.
  2. Large Physical Size: The amplifier’s substantial build may pose challenges for users with limited space in their audio setups.
  3. Complex Features: While the amplifier offers extensive features and customization options, some users may find them overwhelming, especially if they prefer a more straightforward setup.
  4. Tube Maintenance: The need to replace or adjust tubes periodically may be seen as a drawback for those who prefer low-maintenance amplifiers.
  5. Transistor Sound Preference: Users who prefer the characteristics of solid-state amplifiers, such as a more clinical and linear sound, may not find the Integre4 MK2’s tube-driven sound to their liking.

The Lab 12 Integre4 MK2…

  • Pushes and pushes in the deep bass and bass that it’s a real joy. A little care when choosing speakers is advisable.
  • Can therefore be very powerful in terms of gross dynamics and can also achieve surprisingly unlimited level jumps in the middle and upper-frequency ranges.
  • Proliferates with strong timbres that do not obscure details.
  • Emphasizes the upper midrange a little so that voices appear unusually concise and direct. It turns clean and orchestrated music into a real experience – very complex structures at high volumes and unfortunate amplifier-speaker combinations can seem tiring.
  • Plays straight in the treble and not in a typical tube-like manner. It never causes stress; you can also attribute a certain silkiness to it.
  • Plays well in his class in terms of fine dynamics.
  • Analyzes details at a high level, allowing even more expensive amps to gain some traction only in the super-high frequency range.
  • Preferentially reproduces on and in front of the loudspeaker level, which is certainly also due to the generally offensive midrange. With the right material, he can set up the action clearly behind the speakers.
  • Projects individual sound events in eerily sharp outlines and three-dimensional. The stage space remains rather compact, which further promotes the feeling of directness and intimacy.