When I first got into audio, in the late 1980s, few makers of perfectionist hi-fi produced integrated amplifiers, especially here in the United States. Perhaps rightly so: Most audiophiles preferred separates, often mixing and matching components from different manufacturers. The integrateds then available often seemed like design anomalies -- hastily slapped together, serving as stand-ins to round out a manufacturer’s offerings or introduce new audiophiles to the brand.

These days, more manufacturers are giving integrated amplifiers their due, and now a plethora of high-quality, no-compromise models are available, many of the higher-end models containing the same circuit innovations and high-quality parts as their manufacturers’ separates. To match all this, of course, such integrateds also have high prices.


But the audiophile marketplace is also now full of integrateds at more reasonable prices, including many from brands new to me. One example is the subject of this review. Lab12 reveals its Integre4 as offering an interesting mix of reasonable power output, user friendliness, and features for the quite respectable price of $4900 USD, including its tube complement of quartets of 6N1P dual triodes and KT150s power pentodes. Curious to see and hear what the Integre4 was all about, I asked for a review sample. Not long after, one arrived on my doorstep.


Stratos Vichos founded Lab12 in Athens, Greece, with the intention of offering handmade, high-quality, innovative tubed components, and several of the Integre4’s design and operational features seem to support that claim. For example, the Integre4 accepts a variety of output tubes: 6L6, EL34, 6550, KT88, KT120, or KT150. Individual trim pots make adjusting and matching tube bias a breeze. Four independently operating 6N1P tubes serve as the drivers, two tubes per channel. This configuration reportedly helps minimize noise, a primary design goal for all Lab12 products.

The Integre4’s internal construction also appears to serve this goal. The regulated power supply includes 11 high-capacity, low-ESR, Nippon Chemi-Con capacitors, which should help maximize power output and dynamic capabilities. A plethora of high-quality parts populate the neat and tidy circuit boards, including Wima film caps and a motorized Alps Blue Velvet volume potentiometer. A minimalist remote-control handset is included for controlling the volume level, source selection, and menu functions.


The Integre4 boasts the same attention to detail outside as in. All visible surfaces are thoroughly finished, and all joins fit together nicely. The rear panel is carefully thought out, with five well-spaced, single-ended analog inputs (RCA), an IEC power inlet, and two pairs of high-quality speaker terminals.

On the front panel, knobs labeled Navigation and Volume flank a central OLED display. The Integre4 measures 16.9”W x 7.5”H x 11.4”D and weighs 44.1 pounds. It’s a zero-feedback design.

Using the supplied Tung-Sol KT150 tubes, the Integre4’s power output is specified as 65Wpc into 4 or 8 ohms across a wide bandwidth of 15Hz-60kHz, -1dB. Substituting 6550 tubes reduces the power output to 45Wpc, according to the manual; specs for other types of output tube aren’t given.

Setup and sound

Setting up the Lab12 Integre4 was easy and straightforward: Install tubes, set biases, and choose the name to be displayed for each input, if desired. My sample had already been sufficiently run-in by the distributor. Before doing any serious listening, I warmed up the amp for 30 minutes, per Lab12’s recommendation.

From the outset, driving my Klipsch Epic CF-2 loudspeakers, the Integre4 distinguished itself as being the antithesis of the pipe’n’slippers sound often associated with the tube amps of yore. Instead, the Integre4’s sound was fulsome, powerful, and authoritative, with fine dynamics, good extension at the frequency extremes, and excellent timing and rhythmic capabilities.


Taking the last first: In the dance-friendly groove of “Bamboo,” from Elder Island’s EP Seeds in Sand (MP3, Metropolis), the polyrhythmic mix of percussion and layered staccato accents were toe-tappingly upbeat and well organized. The Integre4 had no trouble delivering this tune’s rhythmic complexities with clarity and coherence. Ditto “Gave Your Love Away,” from Majid Jordan’s The Space Between (MP3, OvoSound), which came through with compelling rhythm and pacing without sounding forced or hurried. The Integre4 had so addictively realistic a sense of flow as it moved the notes and beats along in time that I couldn’t help bobbing my head to the music flooding the room.

Because a high quality of bass reproduction is inherent to good timing, you’d expect estimable lows from the Lab12. No surprise -- the Integre4 excelled at bass definition and articulation. In the final movement, Allegro con moto, of Shostakovich’s Cello Concerto No.1, with soloist Alisa Weilerstein and Pablo Heras-Casado conducting the Bavarian Radio Symphony Orchestra (24-bit/96kHz AIFF, Decca), the timpani were realistically textured and appropriately taut for the initial mallet strokes, followed by convincing bloom and decay. Orchestral bass accents also snapped, with clean attacks, providing the perfect dramatic response to the melodic line. Wanting more, I tried one of my go-to SACD/CDs, Joe Henderson’s Lush Life: The Music of Billy Strayhorn (Verve B000138136). Through the Integre4, Christian McBride’s plucked double bass in “U.M.M.G.” was warmly resonant, rich and woody, and clear and nimble, all while keeping perfect time for this upbeat performance.

I was, however, surprised by the quantity of deep bass the Integre4 could produce -- what seemed a never-ending but never too generous supply of well-defined lows. The ostinato synth-bass line of “Hyper-Ballad,” from Björk’s landmark album Post (16/44.1 FLAC, One Little Indian 31), was jaw-droppingly physically visceral, vibrating with equal measure my listening-room walls and my chest. The same thing happened with the bass line of Tessa Thompson’s “Grip” (MP3, Atlantic) -- the sinewy, pulsating beat pressurized my listening room while maintaining fine accuracy of timing and pitch definition. The bass line of Elder Island’s “The Big Unknown” (16/44.1 FLAC, Moda Black) also sounded huge and positively subterranean, while individual notes remained clear and distinct. If big, bold bass is your jam, you’ll find plenty to love in the Integre4. In terms of both quantity and quality of bass, it bettered almost every other reasonably priced integrated amp I’ve heard.


The Lab12’s large-scale dynamics were as good as its timing and bass reproduction. With Mussorgsky’s Night on Bald Mountain, as performed by Esa-Pekka Salonen and the Los Angeles Philharmonic (SACD/CD, Deutsche Grammophon 002894776198), the Integre4 displayed its way with macrodynamics, unleashing the full brunt of this recording’s explosiveness and bombastic impact. The horn section’s shout-chorus accompaniment in “Recipe for Love,” from Harry Connick Jr.’s We Are in Love (SACD/CD, Columbia CS 46146), was also thrillingly climactic, blowing down the walls in the tradition of the hardest-swingin’ big bands. In terms of macrodynamic expressiveness, the Lab12 Integre4 outperformed nearly every sub-$6000 integrated I’ve heard.

I love tubes for their way with midrange tonality. Almost every tube amp I’ve heard seems to get this right, delivering a good dose of midrange magic in terms of tonality and truth of timbre. So it went with the Integre4. While the Lab12’s mids weren’t the most believable or most colorful I’ve heard, they trounced those of many solid-state amps. For example, Chris Isaak’s baritone voice in the title track of his Forever Blue (CD, Reprise 9362458452) was rich, butter-smooth, and well-textured, similar to how it sounded when I heard him live and off-mike as he performed while walking through a crowd. Compared to the best of its brethren, the Integre4 shaved off a bit of harmonic complexity and timbral richness here and there, and ultimately lacked a little refinement and finesse. Still, I find such flaws of omission easy to ignore -- in fact, I never felt anything in this region was missing except in direct comparison with a better amp (see below).

Higher in the audioband, Forever Blue exposed one of the Integre4’s additive flaws. It could sound a bit too enthusiastic in the upper mids, consistently producing excess energy and amplitude in this region, regardless of recording. Isaak’s high sung notes, and the electric guitars in “Forever Blue” and “Go Walking Down There,” sounded artificially spotlit, even a bit strident. So, too, did the strings and vocal in “Paid,” from Sudan Archives’ eponymous EP (16/44.1 FLAC, Stones Throw STH2390).

In an attempt to push the Integre4’s upper mids to their limit, I streamed several tracks from Spotify, itself a bright-sounding platform. With the somewhat mellow-balanced Living Voice Avatar speakers I also own, the voices and guitars in “Don’t Bother Calling,” from Moses Sumney’s Aromanticism (320kbps Ogg Vorbis, Jagjaguwar), sounded fairly well balanced through the mids and into the lower treble. So, too, did SZA’s voice in “Love Galore,” from her album Ctrl (320kbps Ogg Vorbis, RCA). But through the more neutral-balanced Klipsch Epic CF-2 speakers the Integre4 pushed the presence region forward, adding some shrillness and excess sibilance to SZA’s voice. “Birds of a Feather,” from Mocky’s Saskamodie (320kpbs Ogg Vorbis, Heavy Sheet Music), also had a bit of excess glare and brightness in the sounds of tambourines and whistling, sounding at times too harsh.


Curious to hear how the Integre4 might sound with different tubes, I swapped out its stock KT150s for a quartet of current-production EL34s, also from Tung-Sol. The Integre4 makes tube rolling a breeze -- bias adjustments are easily monitored using the front-panel display. I assumed that using KT150s and EL34s made by the same manufacturer would limit any differences in sound to those between tube types, and the Integre4 confirmed that assumption. The KT150s produced a sharper, cleaner, more “modern” sound, with flatter, more evenly balanced mids and better extension at the frequency extremes. The EL34s countered with more air, space, and bloom around instruments, denser tonal colors, and finer harmonic decays, even as the midrange seemed mildly emphasized. For example, Nicholas Payton’s trumpet in “Kamathi,” from his Afro-Caribbean Mixtape (320kpbs Ogg Vorbis, Paytone), sounded fuller, richer, and more rounded through the EL34s, and synth keys had better decay through the vibrato, while bass sounded deeper, tighter, and more powerful with the KT150s. Via the KT150s, however, cymbals shimmered with better extension, and more presence in the mix. Tube rollers, or those looking for an amp that can be easily tailored to their preferences in sound, should enjoy using the Integre4.


Feeling I had a good handle on the Lab12 Integre4’s general sound character, I wanted to hear how it compared with my longtime reference integrated amp, Audio Note’s L3 EL84 Signature. At first, comparisons seemed to favor the upgraded Audio Note, whose parts list includes silver internal wiring, a resistive stepped attenuator, C-core transformers, and a slew of boutique parts that together raise its current retail price to about $7000. Still, I felt confident the Lab12 could hold its own, given what I’d heard so far.

And hold its own it did. As I listened again to SZA’s “Love Galore,” the Integre4 sounded big, bold, and powerful, with plenty of juice to spare. When it came to sheer output and dynamic headroom, the KT150-outfitted Integre4 handily outdid the lower-wattage Audio Note. Even driving the highly sensitive Living Voice Avatars or Klipsch Epic CF-2s, there’s a limit to how hard the L3 can push before its sound starts to harden, even if that limit is at ear-bleeding volumes. Not so the Integre4. It belted out the most bombastic passages of the Shostakovich cello concerto and the Mussorgsky work’s discmate, Stravinsky’s The Rite of Spring, at insanely high levels without distortion or glare. If you crave high volumes and tubes, the Integre4 should handily satisfy both cravings.

The Integre4 also bettered the L3 Signature in terms of bass output. With Björk’s “Hyper-Ballad,” the Lab12 dug deeper in the bottom octave, and with greater volume. Majid Jordan’s “Gave Your Love Away” confirmed the Integre4’s superiority in this regard, its bass sounding consistently tighter and punchier. For good measure, I also replayed Night on Bald Mountain -- the timpani rolls, too, came through the Lab12 with greater force and wallop.

Even so, the Integre4 couldn’t match the Audio Note in bass quality. Regardless of recording, the L3 Signature countered with lows that were more nimble, supple, and better defined through the harmonics. This was especially evident with The Rite of Spring -- the timpani rolls that had sounded more forceful through the Integre4 were more distinctly colorful and richly textured through the L3 Signature. Via the Audio Note, orchestral double basses also bounced with greater verve and clarity through the sustain and decay components. The Lab12 simply sounded less real and believable, more dry, less tonally developed.


Comparing the amps across the rest of the audioband reminded me why I’ve stuck with the Audio Note so long. While the Lab12’s spectral balance was well judged by any measure, it couldn’t match the Audio Note’s. As I listened again to “Grip” through the Integre4, Tessa Thompson’s voice was a bit too far forward in the mix, and the electric guitars in Chris Isaak’s “Go Walking Down There” also sounded noticeably brighter and more glaring. The Lab12 also seemed to shortchange sonic details and articulation, Thompson’s voice missing some of its color, texture, and richness. Switching back to the Audio Note made her sound smoother, more sumptuous, more harmonically complete, with more realistic tone and better enunciation.

Comparisons of the amps’ treble reproduction produced similar results. With “Lost Cause,” from Beck’s Sea Change (SACD/CD, Geffen 493537), hi-hat, cymbals, and guitar harmonics lost some sparkle and airiness through the Integre4, sounding less extended, detailed, and refined than through the L3. The Lab12 also came up a bit short in timing. The Audio Note made the groove-laden beats and highly percussive accents of the title track of Majid Jordan’s The Space Between sound better synchronized in time and thus more rhythmically involving. But the Lab12 was itself no slouch at timekeeping, in which it bettered a good number of similarly priced amps. Had I not directly compared it with the Audio Note, I’d have been entirely satisfied with its rhythm and timing.

In terms of soundstaging, these amps were closely matched. In Chopin’s Introduction and Polonaise for Cello and Piano in C Sharp Minor, performed by Alisa Weilerstein and pianist Inon Barnatan (16/44.1 FLAC, Decca), the Lab12’s soundstaging seemed as wide and as expansive as the Audio Note’s, if with less vivid aural images. The cello resonated with a touch less weight, presence, and solidity, nor was the Integre4 as adept at delineating the acoustic space it and the piano were being played in. Nevertheless, the Integre4 held up well to the L3 Signature’s ultravivid imaging.

Overall, the Lab12 Integre4 proved a worthy competitor to the Audio Note. While it couldn’t match the more expensive amp on every point of comparison, it gave up little sonic ground even on the points it lost, and in absolute terms came surprisingly close to the sound of the L3 Signature. And the Integre4 even scored points over the Audio Note in terms of sheer power output, bass weight, and macrodynamic expressiveness. These factors should be enough to push the Integre4 to the top of the list of those whose speakers aren’t highly sensitive.


All in all, the Lab12 Integre4 was a thoroughly excellent-sounding integrated amplifier. Its powerful, punchy, dynamic sound was a treat for the ears, and its fine timing did justice to all genres of music. While it wasn’t the most refined-sounding tube amp I’ve heard, it was one of the most enjoyable. What’s more, its ability to drive reasonably sensitive speakers to uncomfortably high volume levels without distortion should make it a no-brainer for anyone considering a tube amp in this price range. Throw in its user-friendly interface, its large, easy-to-read display, and its ability to accept many different tube types, and the Integre4 might be the most versatile, well-rounded tube amp anywhere near its price. If you’re looking for an integrated amplifier for around $5000, the Lab12 Integre4 should top your audition list.

. . . Oliver Amnuayphol

Associated Equipment

  • Loudspeakers -- KEF R700, Klipsch Epic CF-2, Living Voice Avatar
  • Integrated amplifier -- Audio Note L3 EL84 with Signature upgrades and C-core transformers
  • Phono preamplifiers -- Audio Note L3 Phono Stage V2 with Signature upgrades, Parasound Halo JC 3 Jr.
  • Step-up transformer -- custom-made Sowter Magnetics 9570 (1:10)
  • Sources -- Denafrips Ares DAC; Apple MacBook Pro laptop running JRiver Media Center 20, Sony SCD-XA777ES SACD/CD player, Rega Research RP8 turntable with Lyra Delos cartridge
  • Interconnects -- custom single-core, copper coaxial (RCA); Blue Jeans Cable LC-1, Wireworld Starlight 7 (USB, coaxial)
  • Speaker cables -- Tellurium Q Ultra Black, Wireworld Oasis 6
  • Power cords -- Wireworld Aurora 5.2 and Electra 5.2
  • Accessories -- Music Hall WCS-3 record cleaner, Clearaudio stylus cleaner, Mobile Fidelity Sound Lab record brush

Lab12 Integre4 Integrated Amplifier
Price: $4900 USD.
Warranty: Five years parts and labor; 90 days, tubes.

K. Varnali 57A
Metamorfosi, Athens 14452
Phone: +30 2102845173

E-mail: contact@lab12.gr
Website: www.lab12.gr