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
TK One 211-i
reviews
Manufacturer details
- Tubes: 211 x 2 – ECC82 x 2
- Inputs: 3 line inputs
- Signal input: 400 mV for max power
- Output Power: 16 W / Channel
- Output Impedance: 8 ohm
- Frequency Range: 15 – 35.000 Hz
- Power Supply: 100/115/230/240 VAC – 50/60Hz
- Dimensions: 42 x 28 x 25 cm
- Weight: 30Kg
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:
Select products
TK One 211-i
- Positioning: The entry-level integrated tube amplifier tailored for affordability and simplicity.
- Description: Built with 211 tubes and ECC82 preamp tubes in a compact, point-to-point construction ideal for small rooms and straightforward setups. Compared to the KT150 or 6550 variants in the TK One line, it represents a more accessible option, and relative to the TK Two series, it offers fewer functionalities and lower power output for budget-conscious buyers.
TK One KT150-i
- Positioning: A mid-range integrated tube amplifier from the heritage classic range.
- Description: Features KT150 power tubes in a single-ended design with point-to-point wiring and a solid wood finish that provides reliable performance. In comparison to the entry-level 211-i, it offers refined audio qualities, while against the more advanced 6550 variant, it represents a balanced choice.
TK One 6550-PSE
- Positioning: A premium integrated amplifier from the heritage classic lineup featuring 6550 technology.
- Description: Uses 6550 power tubes in a handcrafted, point-to-point built design that delivers a distinct tonal character and clarity. When weighed against the KT150-i, it offers upward refinement in sonic detail, yet it remains less complex than the TK Two series for users who prioritize traditional tube warmth with moderate output.
TK Two KT150-PSE
- Positioning: A high-performance integrated tube amplifier in the heritage evolution series.
- Description: Uses four KT150 tubes in a single-ended parallel design with automatic bias, a VU meter, and remote volume control to deliver improved power and control suited for larger rooms. Compared to the TK One models, it provides enhanced functionality and performance, while it remains a step below the flagship 211-PSE in terms of output and manual control options.
TK Two 211-PSE
- Positioning: The flagship integrated tube amplifier in the evolutionary lineup with maximum power output.
- Description: Uses a combination of four 211 tubes and three 6SN7 tubes with a manual bias system featuring precision controls, resulting in groundbreaking sonic authority ideal for larger spaces. Relative to the TK Two KT150-PSE, it offers higher output and detailed manual adjustments, and when compared to the TK One offerings, it delivers more advanced features and increased power for discerning users.
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Used
Tektron
What if you spend more?
Features Matched tubes: 211 x 2 – 6SN7 x 2 Inputs: 3 line inputs rca + 1 xlr Signal input: 400 mV for max power Outputs: 19W / Channel Bias: automatic Volume: Stereo volume control with high quality potentiometer with remote control Connectors: Input connectors high quality Outputs impedance: 8 ohm (other impedance available upon request) Frequency range: 14 – 36.000 Hz Power Supply: 100/115/230/240 VAC – 50/60Hz. Other voltage are available upon request.
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Product Strengths
- Beautifully crafted with Italian manufacturing traditions integrating form with style
- Offers a warm and balanced mid-range, a fulsome projection, and reproduces authentic resonance
- Macrodynamics are represented with a clear, yet golden glow typical of SET amps—but with a bonus from the 211 power tubes
- Creates a substantially open and spacious soundstage, augmenting the perception of depth and instrument placement
- Renders the graininess of the violas and the cellos beautifully, which sounds natural and musical
Product Considerations
- The expense of replacing tubes is a serious concern
- SET amps require speakers of very high sensitivity (93dBs and above)
- The bass is perhaps slightly muddied in spots
Takeaway: The Tektron Italia Neptune is a sophisticated Italian-made amplifier where design and function follow the higher spirit of beauty and style. The engineering offers the best of 'tube' consciousness and listening experience.
Video review
Our take on the brand
Features Matched tubes: 2A3 x 2/4 (OR 45 x 2/4, OR 50 x 2/4, OR 300B x 2/4) – 6SN7 x 2 – 5V4 x 2 – 6X5 x 1 Inputs: 3 line inputs Signal input: 400 mV for max power Outputs: 1.6W / Channel with one 45 — 3.6W / Channel with two 45 3.5W / Channel with one 2A3 — 7W/ Channel with two 2A3 5W / Channel with one 50 — 10W with two 50 7W / Channel with one 300B — 14W / Channel with two 300B 9W with one 300B XLS / Channel — 18W / Channel with two 300B XLS Outputs impedance: 4 – 8 ohm (other impedance available upon request) Frequency range: 15 – 35.000 Hz Power Supply: 100/115/230/240 VAC – 50/60Hz. Other voltage are available upon request
Product Strengths
- A variety of tubes can be used (45, 2A3, PX4, PX25, 300B, or 300B XLS) to produce different power outputs (1.5 to 22wpc)
- It can operate in single-ended (SE) or parallel single-ended (parallel SE) mode
- It is very adaptable—allowing for changes to input tubes and 5AR4 rectifiers to alter the amp's sound
- Built-in bias meters and pots allow for re-biasing when changing tubes
Product Considerations
- The right speaker load (high output impedance) is needed to perform optimally
- Single-ended amps shun negative feedback, which would lower their output resistance
- Speakers not well-suited for high output impedance amps may experience premature bass roll-off and a rising presence response
Takeaway: The TK2A3/300PSES-i Ref amplifier offers a lot of flexibility for tube rolling and sound customization. It is well-suited for high-efficiency speakers.
Video review
Our take on the brand
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With the inclusion the new tube cage, the transformer cover was raised 2" to allow the cage to fully protect any KT-120/KT-150 tube. The resulting metal work and power supply changes have yielded our quietest Nautilus yet. Many still love the sleek lower profile look of the Classic Nautilus and as such we allow you to order your Nautiluswith the original metal work style or the Rev 2. The Classic Nautilus will additionally save you $1000 on the purchase.
The Story of the Nautilus is born of the same process that brought the Zions. We set out to build my private amps apart from ampsandsound. These were to be mine without branding and never to leave for demos. All too often, my own listening space was sacrificed for the need for demo stock. I chose the HK Cit II as my inspiration point. From that seed came my own Cit II Monos build on turrets just like the best amps of the golden age.
The Nautilus brings the dual-mono layout onto a single chassis. We started with our most versatile circuit, the Mogwai, and went about creating two separate amps that share a single chassis. 2 Power Transformers, Separate Power Supplies, Chokes, and input transformers. The amps are built with separate turret boards, with the shared component being the input tube, volume control, and outputs.
The Nautilus is a classic and decidedly prosaic design, as it employs turrets and point-to-point wiring & there is no silicone, ICs, or regulators. We consider this a standard-bearer of purest audio with an American sensibility. The Nautilus is built in a way few modern amplifiers are. This is not due to intrinsic inferiority, but rather it is impossible to rush and is incredibly expensive to produce.
The Nautilus has been described as a tube integrated amp for personal audio users. We mean by this, the Nautilus allows for five separate impedances to be selected for system matching and has a pair of 8ohm 5 way binding posts. The speaker vs. headphone output is selected with a small toggle switch on the back of the amp.
Product Strengths
- Five individualized outputs with different impedances
- Custom wound ultra-high quality output transformers provide excellent frequency extension and a flat response
- Engaging audio components offer superior sound quality using proven theories, solid engineering, and quality manufacturing, all taking place in the USA
- Brings out the very best qualities in all of the headphones tested, providing the best presentation ever heard from the Aeolus
- Build quality is a step-up from other amplifiers
Product Considerations
- The most expensive quarter inch plugs you can get, have locks on them, which can be annoying
- Unplug headphones before switching to speaker outputs
- Weighs around 68 pounds and around 93 pounds shipped in its large pelican style case—it is heavy
- Can clip when used with speakers if pushed too hard
Comparisons (according to reviewers)
- Nautilus sounds better than the ZMF Pendant Headphone Tube Amplifier and the Mogwai OG Tube Amplifier in every regard
- Nautilus is even more comprehensive and expressive through the powerful, well-controlled, tonal density that is detailed and rich in nuance—it has more extension and top-notch resolution
Takeaway: The Nautilus seems to be a versatile amplifier that brings out the best in headphones and speakers. It's built with quality parts and offers a lush and detailed sound experience for audiophiles who want to enjoy music to the fullest.
Video review
Our take on the brand
Double the Performance Trouble-free, noise-free, and double the power of traditional 300B amps. Made possible by patented circuit design. A New Classic We’re proud to continue a legacy of quality, American manufacturing with innovative new features. Ships with Tubes The 91E ships with new production 300Bs, the most popular electron tubes in the world. Made in the USA.
Product Strengths
- New patented design SCS (source current steering) allows the amplifier to have a fabulous bottom end without affecting the glorious midrange
- Proprietary noise reduction system eliminates noise that can be inherent in a single-ended design
- Circuit protects the 300Bs and keeps them in their safe operating range, so there is no chance of damaging the tube or having a shortened life
- More power from this amp than a traditional 300B, it's the difference in presentation
- It has Bluetooth, phono stage (moving coil and moving magnet), and wireless remote control
Product Considerations
- Instructions could be a little clearer about installing the 300Bs
- More warm-up is needed for each listening session than originally allowed
- The 91E was designed for operation with Western Electric manufactured 300B electron tubes
- The brands and specifications of the capacitors, resistors, transformers, internal wires, RCA jacks, switches, and binding posts are not disclosed
Comparisons (according to reviewers)
- Vs WE 91A: 91E retains what's best about the early WE 91A—its delicacy, bloom, openness, and tonal magic—and adds modern improvements
Takeaway: The Western Electric 91E is a uniquely designed amplifier providing great sound with modern features like Bluetooth and remote control, pushing what a 300B tube amplifier can achieve. It's a great option for audiophiles wanting to step up from other tube amplifier sounds.
Video review
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What competes at this price?
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Our Summary
Product Strengths
- Addictive sound signature, unlike any other amp, with otherworldly instrument and voice reproduction
- Delivers serious magic with Fleetwood Deville and Klipsch Heritage speakers, revealing obscure details and creating a massive soundstage
- Dynamics for days
- Combines the qualities of a nice SET amp without the downsides, like noise or tube replacement
- Exceptional build quality and design with high-quality parts
- Only has two RCA inputs, no XLR balanced connections
Product Considerations
- Heavy speaker cables can cause the amp to tilt
- The volume dial functions as a gain dial, which may be different than what some users are accustomed to
- May not be suitable for hard-to-drive speakers in the 85db range that dip into 2–4 ohms
Comparisons (according to reviewers)
- The AMP23R offers more texture, layering, mid-bass, and vocal presence than Nagra INT
- The AMP23R is more organic, ethereal, and dynamic than Kinki Studio EXM1
- It sounds better than the Vinnie Rossi L2iSE, so long as the speakers are easy to drive
- The Enleum has more delicacy and finesse than Pass Labs and Cary Audio
- The AMP23R stacks up with the finest gear such as ampsandsound Bryce monoblocks
- Pass Labs First Watt SIT-3 offers a bit more organic, warmer presentation
Takeaway: The Enleum AMP-23R is a small but mighty integrated amplifier with a unique and addictive sound signature, and it is built with high-quality components. It's a great choice for those with sensitive speakers looking for a reference-quality system in a compact package.
Video review
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Our Summary
Product Strengths
- Very powerful amp with crazy headroom, capable of driving most headphones, including those that need a lot of power, and can grow with you as different headphones
- Delivers clarity, separation, detail, and impact, making every pair of headphones sound better
- Multiple impedance outputs allow dialing in the best sound for a given pair of headphones
- Super black background—very low noise floor
- A ton of different tubes can be rolled, including EL34s, KT66s, KT67s, KT88s, 6550s, and KT90s, making it very versatile and allowing customization of the sound to exact taste
Product Considerations
- Only one input via a pair of RCA connectors
- Requires a pre-amplifier or DAC with volume control if obtained without the volume pot
- May lack convenience features because of ampsandsound's minimalist philosophy
- Can be very heavy
Comparisons (according to reviewers)
- Vs Linear Tube Audio's Z10e: Z10e seemed more focused and brightly lit through the midrange
Takeaway: The Bigger Ben is a hugely versatile and powerful amplifier that could be an end-game amp, especially if you want to experiment with tube rolling. Its sound is detailed, clear, and engaging, making it a great choice for anyone who loves listening to music.
Video review
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Our Summary
Product Strengths
- Wide and deep soundstage, with a depth extending as far as 70 feet in one test
- Music reproduction is natural and realistic, creating a sense of instruments and voices being present in the room
- High frequencies and cymbals shimmer and crash realistically
- Impeccably constructed and manufactured with original circuit solutions
- Capable of drama, delicacy, and danger which transcends reproduction — turning the act of listening into a full-fledged experience
Product Considerations
- Selector knob on top of the unit is difficult to access when the tube cage is installed
- Speakers need to be a good match for the amplifier's 23 watts of power
- Bass was shy and ill-defined when used with the Dynaudio Contour 60i speakers
Comparisons (according to reviewers)
- Compared to Conrad Johnson Premier 10 & 11A, the Simply 845 has a wider and deeper soundstage and better reproduction of high frequencies and cymbals
- Compared to PrimaLuna (top-of-the-line), the Simply 845 sounds better sonically
- Compared to Line Magnetic Audio LM-845iA Integrated Amp, the Simply 845 does delicate better
Takeaway: The Simply 845 is a revealing integrated amplifier that makes music sound magical and is an excellent choice, especially for horn speaker lovers. This amplifier transforms speakers into something wonderful and will enhance the music experience.
Video review
Our take on the brand
Our Summary
Product Strengths
- Refinement and smoothness in sound
- Exceptional build and finish, including exquisite woodwork
- Seductive midrange and overall musicality
- The Sinfonia has a romantic, addictive sound that's better suited to classical music
Product Considerations
- Not the last word in slam
- Needs careful system partnering to sound its best
- Dynamics were very good, although not exactly of the same caliber as with the ModWright preamp and amp
- When pushed to the extremes, during the most dynamic passages, the Sinfonia began to reach its limit—compressing gently and giving up some of the low frequency control
Comparisons (according to reviewers)
- Sinfonia offers a smoother, warmer, and more seductive sound, while the S6 amplifier sounds a little 'faster' and more linear
Takeaway: The Sinfonia is a fine amplifier with a beautiful build that delivers a refined and smooth sound. It's a good choice for enjoying music and will make your eyes smile with its hand-made Italian design.
Video review
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Our Summary
Product Strengths
- Exceptional build quality and aesthetics
- Delivers a robust 40 watts per channel into 8 ohms
- Demonstrates remarkable frequency handling, extending from 17Hz to 63kHz (-2dB)
- Precise bias adjustment with built-in meter
- Superb control, power, and effortless flow
Product Considerations
- Relatively heavy at 30kg
- May require occasional tube maintenance
- Power output might not suit all speaker combinations
- A softer 300B glow was not present
Comparisons (according to reviewers)
- The Triode as amp offered a similar kind of finely grained nearly neutral sound as the Audionet
- No amp has bettered the Riviera Levante integrated amp in dimensional quality
- Parts cost plus the Evolution comes with two Western Electric 300Bs that run $1499 per matched pair on the open market, while the Triode TRZ-300W sports four Triode-branded 300Bs
Takeaway:
The Triode Evolution is a high-end tube amp that delivers music with power and clarity. Those who value musical authenticity and appreciate the warmth of tube amplification may find it a great fit.
Video review
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