KAEI Design TAP2 Review: Awesome vintage memories!

KAEI Design TAP2 Review

Portable headphone amplifiers are gaining popularity like DAC dongles in the audiophile community day by day. Though they are not that small compared to DAC dongles, their mobility is great. KAEI Design TAP2 is a small portable audio gadget that has two variations: only an amp, and a DAC & amp. The stock one has only a single-ended output and has two modes: tube & solid-state. So, it’s more like two-in-one. I spent more than three weeks with this little but powerful amp and tested it with every source I have. The sound from both modes are superb, and you will fall in love with this amp in no time. But there are some downsides also, which I will cover in a different section in this review.

Hisenior Mega5EST

DISCLAIMER

KAEI Design was kind enough to send me the TAP2 to review. I am not affiliated with KAEI Design, and of course, I was not asked for any copy-checking before publishing. All opinions shared in this ‘KAEI Design TAP2 review’ are my subjective thoughts.

One thing more: The review is based on my personal experience and what I hear using different sources. Your experience may vary because of personal preference and physical differences like the shape & depth of the ear canal.

For your personal purchase, checkout GEEK MART or KAEI Design for their fantastic products and promotions (non-affiliated links).

PAIRED WITH

●   DAP: Cowon Planue R2, Cayin N3 Ultra, iBasso DX180
●   DAC: xDuoo XD-05 Plus, Cayin RU7, iBasso DC04 Pro, Dunu DTC 480, Fosi Audio DS-1, Celest CD-10, Celest CD-20, Hidizs SD8 Pro Robin, Moondrop Dawn Pro.
●   IEMs/Headphones: Audiotechnica M20X, M50X, Kinera Verdandi, Hisenior Mega5 EST, BQYEZ Frost, Winter, AFUL MagicOne, Explorer, Performer 5, Performer 5+2, Cantor, Hidizs MP145, Ikko OH10, 10s, SeeAudio Rinko, Tinhifi C2 2025, Juzear Dragonfly 81, Dunu Falcon Ultra, Titan S2 etc.
●   OPAmps: OPA2132 (Stock), TI BB OPA 2604, Muses 8820
●   Files: Spotify & local Hi-Res FLAC & DSD files.

TECHNICAL SPECIFICATION

● Tube: Dual JAN 6418 tube
● OPAmp: OPA2132
● Headphone output thrust: 1000mw L+R (30Ω)
● Support impedance: 6-600Ω
● Distortion THD+N: around 0.001 (2V)
● Input Connector: 3.5mm
● Output Connector: 3.5mm
● Battery capacity: 4000mah
● Operating time: 12 hours
● Charging time: 4 hours
● Weight: 260g/0.6lb
● Exterior: Metal
● Replaceable op-amp: dual op-amp can be replaced

WHAT’S IN THE BOX

● TAP 2 AMP
● Aux Cable
● Type-C charging cable
● 2pcs. Rubber band

The size is like all other common portable headphone amps in the current market.

BUILD & DESIGN

This amp is a very well-built one, just like their other products. The entire exterior is metal-built with a transparent window for the tubes to display. It feels solid in the hand and has a weight of 260 grams, which helps the device to be labeled as ‘portable amp.’ The front and rear panels have all the connectivity, switches, & nobes you need to operate the device; nothing on the side. This is a good approach. I personally don’t love devices with side buttons because sometimes you may press them accidentally.

In the front panel, there is a volume knob (which is also on-off) in the middle. On the left, a 3.5mm line in and DAC/Line (Amp) selection switch. My unit has no DAC installed, so I always keep the switch in ‘line’ mode. There is a Gain (10 dB-0 dB) switch and a 3.5mm HP output on the right side. If you wish to have a 4.4mm jack (not balanced), they will modify your unit before shipment. In the rear panel, you will find the type-C charging port, a solid state/tube amp selection switch, and a USB-C line-in port. The design is very thoughtful and user-friendly, in my opinion.

INTERNALS

TUBE: The TAP2 has two JAN 6418 tubes installed inside. This is a subminiature pentode vacuum tube, originally developed for military applications. This is suitable for portable amplifiers for two very impactful reasons. First, its minimal filament and plate voltage requirements enable extended battery life. And second, its subminiature construction allows for integration into small, portable designs without compromising performance. When it comes to sonic performance, these little tubes are capable of delivering a very clear and warm sound that will remind you of those vintage ‘tuby sounding’ amps.

But the downside is it is very microphonic sensitive. Meaning, it picks up and amplifies mechanical vibrations that potentially affect sound quality. This issue can be mitigated with proper circuit design and mechanical damping. Sadly, this issue is present in KAEI Design TAP2, as there is no shock absorber nor any kind of damping.

OPAmp: The OPA2132 is a high-performance dual operational amplifier from Texas Instruments, designed with FET inputs to deliver exceptional audio quality. The combination of low power consumption, high slew rate (for accurate & dynamic sound reproduction), wide bandwidth, and minimal noise and distortion makes it an excellent choice for portable amplifiers, where both performance and efficiency are paramount.

When it comes to sound delivery, this OPAmp is known for its balanced audio presentation with realistic, tight bass and detailed highs. Its neutral tonality ensures that vocals and instruments are reproduced with clarity, providing an accurate representation of the source material.

SOUND IMPRESSIONS

TAP2 is a versatile amp with the combination of tube & solid-state technologies. It features JAN6418 tubes and OPA2132 for tube & solid-state amplification, respectively. They sound different, and it’s audible. When you turn the ‘tube’ on, you will feel soft and mellow sounds filling your ears, with spongy bass and melodic mids and highs. With ‘solid-state’ on, the sound will become more bold with thumpy bass region and shiny mids and upper frequencies. I really enjoyed the two characters in one amp.

As my unit is just the headphone amp without any DAC, I used almost all DACs in my possession to test it. I will describe the difference between various DACs I paired it with in a different part of this review. And I will explain the whole sound section divided into two parts: tube & solid-state.

Remember to warm-up the tubes for atleast 5 minutes before you start playing music.

LOW FREQUENCY

TUBE

Soft & mellow—that’s all I can say about the low frequencies in tube mode. The first time I switched this amp in tube mode, I was really looking forward to hearing the renowned warmth the tubes bring into the audio. Settling in with some of my favorite tracks, the bass seemed to take on a smoother, slightly more relaxed character. Low end felt warmer, providing a comforting depth that elevated the effect of listening altogether. The difference was appealingly audible: Bass loosened up and slowed down just a bit compared to the solid-state mode. This gentle shift in sound lent a certain retro appeal to the music; each session seems to be one-of-a-kind enjoyable.

SOLID-STATE

Immediately I noticed that the bass performance completely changed when in solid-state mode. The low frequencies became tighter and better-controlled, allowing them to be punchier and more accurate. That better clarity then made it easier for me to discern all sorts of intricate bass lines, adding to the overall fun during my listening sessions. The extra clean and detailed presentation that solid-state mode provided was perfect for those tracks where ultimate bass accuracy was important.

MID FREQUENCY

TUBE

Operating in tube mode, the KAEI Design TAP2 amplifier offers a mid-frequency characteristic of being warm and full-bodied, enhancing the naturalness of vocals and instruments. The JAN6418 tubes presented a smooth, engaging midrange that makes sessions quite a listening pleasure. The TAP2 strikes a good balance between crisp and smooth in its sound signature, complementing the midrange frequencies. Its balance is perfect in order for vocals to sound clear and emotive, while instruments can remain distinct in the mix. Tube amplification gives a light harmonic richness in the mid frequencies and places the vocals and instruments in space farther back.

SOLID-STATE

Mids were more in evidence and more nuanced with solid-state operation. Vocals and instruments shone more clearly. A further result of this increase in dynamic presence was that the music seemed more immediate—the performers were crouched right before me. The midrange was cleaner and truer in solid-state, and that is what I most enjoyed from vocal and acoustic-instrument genres. That mode was also more transparent, and I was able to appreciate small details and textures within the midrange that simply made a musical message whole.

UPPER FREQUENCY

TUBE

I find that the KAEI Design TAP2 amplifier presents the treble as moderately tamed for a much smoother and more relaxed upper frequency presentation in tube mode. Many tube amps soften the treble, and this is one of the niceties for which they are known. Indeed, it was this smoothed-over treble response that allowed longer listening with less fatigue, since the softened highs didn’t have the potential to become as tiring. There was still some sparkle and airiness within the upper frequencies that were lost to this taming effect.

SOLID-STATE

I changed my KAEI Design TAP2 amplifier to solid-state mode, and there was a transformation of the upper frequencies: the treble became more extended and detailed; cymbals and high-hats were allowed to shimmer with clarity. It’s that enhanced precision that gives music air, opening it up to be more alive. In solid-state mode, the high end was cleaner and more accurate, which is something that I rather enjoy. Where there is enhanced transparency, like in this mode, one can enjoy subtle nuances and textures at the upper frequency that make the listening more rewarding.

SOUNDSTAGE & SEPARATION

TUBE

The KAEI Design TAP2 does quite a lot right in tube mode, especially when it comes to soundstage and instrument separation. It presents a wider-than-usual soundstage, enhancing the spatial distribution of audio elements. Instrument separation is another stronghold for the TAP2, performing close to the best neutrally tuned in-ear monitors out there. One can easily cut through to each instrument within the mix. In tube mode, soundstage width and separation are reduced by only a little. Tube mode warms the sound, adding richness, which may take a slightly different spin on the spatial characteristics of the sound.

SOLID-STATE

With this amplifier in solid-state mode, the sound is emphatically clean and of very clear definition. The soundstage dramatically opens up, becoming wide and spatially open, with every instrument settling into its clear and distinct space. This openness furthers the listener’s perception of an instrument’s positional relationship and movement across the audio spectrum. For all intents and purposes, the TAP2 does an excellent job of separating instruments. If there is a complicated arrangement, it is not thrown into an unresolvable mush but lifted clear with fine detail. Bass and midrange separate well, with no noticeable bleed-through to mute either the clear and distinct vocal or instrumental presentation.

TECHNICALITIES

The performance of the KAEI Design TAP2 is quite versatile in both modes; it’s pretty easy to switch between a warm, musical presentation and an analytic, precise experience, depending on one’s preference.

DYNAMICS

● Tube Mode: One finds it rather engaging and warm in this setting. The tube amplification adds a slight harmonic richness to it, further enhancing the musicality to create an even better experience for the listener.

● Solid-State Mode: It provides a more neutral and precise dynamic response. The solid-state circuitry makes sure of the accurate reproduction of the dynamic contrasts and, hence, should be fit for genres which demand much fidelity and detail.

SPEED

● Tube Mode: Transient response in tube configuration is slightly laid back, helping to build a smooth signature. That gives it some apparent speed, which may prove to be a bit slow. That, however, helps add to the general warmth and personality of the sound.

● Solid-State Mode: It has a faster transient response. It can breeze through difficult passages in music with fast and precise changes of pace. It sounds clean and detailed, which also fits perfectly with complex compositions.

ANALYTICS

● Tube Mode: It plays musically and pleasantly in this tube mode but softens the details somewhat analytically. The result is a more forgiving listen-in, one that was preferred during longer sessions where musicality might be placed ahead of clinical precision.

● Solid-state Mode: The solid-state setting broadens the analytical capability via increased detail retrieval and clarity in this amplifier. This is good to go for critical listening if one wants transparency and accuracy.

PAIRING

I paired the TAP2 with almost all the gear I have. From the DAC dongle to my DAPs, I tried everything. In the following section, I will describe my experiences.

DACS

The unit KAEI sent to me has no DAC installed, so I pair different DAC dongles to find the best match.

● Cayin RU7: Every IEM I tested with this setup shows a good presentation both in tube & solid-state mode. Bass stays controlled, and highs come out so smooth. But the midrange feels a bit forward, especially the vocals. RU7 used to deliver awesome separation & stage. And with TAP2, it hits a different mark with fantastic, spacious presentation.
● iBasso DC04 Pro: Everything came out just right. It shows its ability to deliver thumpy mid-bass as always. And the vocals were in the perfect place in the composition with a wide stage and commendable separation between instruments. Highs are also remained smooth.
● ifi HIP DAC 2: The story is different here. It feels like a totally analog kind of experience with soft & mellow sub-bass, textured mid-bass, nice midrange & high-frequency presentation. The separation & stage is also remained fantastic. And the real magic happened when I turned the ‘X-Bass’ on. Oh man, the whole presentation became so warm and musical. This pairing is my personal favorite.
● Dunu DTC 480: This DAC tends to give a balanced presentation, and it did the same here. I enjoyed the session with this pairing.
● Celest CD 10: Almost like the DTC480, but here the highs were presented with rich texture, and sub-bass lacks a bit of warmth. But you can easily overlook it.
● Fossi Audio DS 1: Ah, one of my favorite DAC dongles. The note weight was too tasteful. The male vocals came out as thick as I like them to be. The bass region reproduced with the perfect warmth but no bleeding into the mids. The highs were smooth and airy. This is my second personal favorite pairing.

DAP/AMP

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● Cayin N3 Ultra: I’ve got the true ‘analog’ experience when I paired the TAP2 with my N3 Ultra (in tube mode). I felt like the song ‘Yesterday Once More’ by Carpenter, and the listening sessions remind me of my childhood when we used to listen to vinyl records. And yes, all those old memories came back clearly to me. It’s totally a different experience.
● Cowon Planue R2: Fantastic, in one word. R2 is not that powerful, so I need to raise the volume in TAP2, which is a big discomfort because of the microphonics of the tubes. But in solid-state mode, it’s all OK.
● xDuoo XD-05 Plus: This pairing also gave me a fantastic experience. Especially the lower region. It’s not overtaking the whole music, but it stays bold and textured while mids and highs are also balanced. Vocals, both male & female, sound so fantastic with this set-up.

IEM & HEADPHONES

I only have two headphones, which I use for audio editing purposes: the Audio-Technica M20X & M50X. These two show a good match with this amp. The tube microphonics are less audible with these headphones. When it comes to IEMs, my AFUL MagicOne & Hidizs MP145 show almost the same performance as the headphones and have less audible tube microphonics. Other IEMs I tried (more than a dozen!) had tube microphonics that were too audible. But in solid-state mode, there is no problem at all. And overall, I enjoyed every IEM and headphone I used with this amp. It’s more like discovering your gear in a new way.

PERSONAL EXPERIENCE

First of all, it sounds great out of the box when you select the solid-state mode, but it’s a challenging situation when you use this amp in tube mode due to its microphonics. There is no shock absorber to reduce this.

CHALLENGES

The main challenge is the tube microphonics. If you tap the body softly, even if you move anything from the surface where you place this amp, you will hear a ‘peeeeee’ type of disturbing sound, which will go away within 30 seconds if you don’t touch it again. And when you turn it on in tube mode, from the very beginning, you will hear some background noise. But the thing is the microphonics are more audible in certain volume positions, like 11 o’clock and 2 o’clock positions. I tried silicone tape, shockproof foams, and even changed the wire on the tube; nothing helps.

HOW TO OVERCOME

In solid-state mode, everything is perfect. But if you wanna enjoy the tube sound, you need to follow some rituals. First, plug everything in while it’s turned off. After turning it on, don’t raise the volume; first play the music and then raise the volume. Then you will not hear that microphonics that much. And after using it for more than half an hour, the background noise will have disappeared as the tubes will have the perfect heat for operation. And in the 9 o’clock, 12 o’clock, and 3 o’clock positions of the volume knob, the noise is less audible..

One thing to remember: always place it on a rubber or foam surface if you wanna enjoy it only in tube mode.

CONCLUSION

It’s a bang for the bucks if you consider the price. And if you think that only solid-state is good for you, then it’s an amp to consider. But if you like me and are obsessed with tube sound, then you need to keep those challenges in mind. But before you take any decision, don’t forget to have an audition. Will I recommend this? off course, but not as a blind buy.

RECOMMENDED FOR

● Who loves quality bass.
● Who loves melodic & texture mids & highs.
● Who loves close to real vocals presentation.
● Who have warm, analog sound.
● Who loves to explore diffrent audio gears.

NOT FOR

● Those people who don’t like hessels of modifying gear.
● Those people who don’t like single ended setups.

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