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Astell&Kern SEM Module for the SE180 DAP Comparison & Review

SE180 with SEM cards

All the Sounds with all the SEMs

People like to customize according to their preferences. This is an essential behavior of human nature. How do you make something uniquely yours? Astell&Kern has released yet another module for the popular SE180 DAP music player - for a total of four current options to tailor your sound to your liking: the SEM1, SEM2, SEM3, and SEM4. Each removable module provides a distinct sound signature for your SE180, from warm and musical (SEM2), to balanced and resolute (SEM1), a more analytical offering with plenty of top-end sizzle (SEM3), and now another offering on the warm side with the new SEM4.

Replaceable modules aren't anything new in the world of portable music players, but Astell&Kern has finally put their own flair on the design. The Astell&Kern A&futura SE180 DAP implements this new design for the company, giving the user complete control to change the sound of their music according to their own listening preferences. Why? Because everyone hears differently.

People like choice, and the SE180 digital audio player departs from the design of the SE200, and instead of including multiple digital-to-analog converters in a single device, they have designed the music player to have removable DAC modules. It's not the first time we've seen this design, but Astell&Kern makes it their own and does it well. Now they've released the SEM4, the latest module for the high-resolution music player. How does it compare? And will there be more on the way?

Riff

Notes

Riff Notes  

Pros

  • Replaceable modules are compact
  • Snug and secure connection
  • Great sound
  • Customization

Cons

  • Pricey
  • Can be difficult to unlock and swap out

Materials & Quality

Like the Astell&Kern SE180 music player, each SEM module is made with matching aluminum, disappearing into the design when installed. The fit is so precise that it's hard to tell if the module is removable at all. The craftsmanship, in general, is superb, with each button finely cavity milled out for seamless precision. The double-locking mechanism is effective in making sure you have a tight and secure fit of the module inside the music player. The module itself connect to the DAP circuitry by means of a USB-C connection, allowing for fast transfer speeds between the DAC and headphone amplifier sections.

With the detachable module section, the DAP is no heavier than a similar weighted player like the SP2000. It's not unwieldy by any means, but there is some weight involved when considering the overall portability of the device. We certainly recommend using a leather case on the device to protect your investment, because it's not so much the fear of dropping the device as it is scratching the glossy front and back glass finish.

Size-wise, it is also comparable to the SP2000, sharing the larger chassis when set side-by-side to the SA700 or SR25 MKII. Still palm-able, the SE180 is the player to beat when it comes to the overall customizable sound that you can tailor to your own listening preferences. The only downside is that the module fits so precisely inside the music player that it can sometimes be difficult to eject. You'll need to find the right angle where you can apply enough pressure on each side of the unit which gives you enough clearance from the locking mechanisms while simultaneously using your fingers or fingernails to pull the module out from the small groove located on the back. After a couple of times of struggling, I found what worked best for me and haven't had any issues since.

Each SEM card has a similar I/O configuration, consisting of a 3.5mm unbalanced headphone jack, and a 4.4mm, and 2.5mm balanced headphone jacks. The power button remains in the same location on the right-most spot on the top of the module. Also, each SEM module attaches to the SE180 DAP via a USB Type-C connection located on the bottom of each card.

As expected, all the SEM cards have the exact same dimensions and build quality. You won't find anything different here other than the superb build quality that Astell&Kern is known for.

SEM cards side by side
SEM Module Family Portrait

Sound Quality

SE180 DAP with DAC cards

The SE180 DAP comes packaged with the SEM1 module, which is equipped with the flagship ESS ES9038PRO DAC chip. These days DAC chips are just a part of the sound signature equation, and one thing that the SE180 boasts that other DAPs can't is a completely separated DAC section from the rest of the machine. This means that the power and RF signals/noise from the main unit is completely blocked by the engineering design of the DAP. Less noise also means a more pure auditory experience. The ES9038PRO is an excellent DAC, providing a surprising amount of detail and clarity to your digital audio. I would say it's on the analytical side of balanced, but not totally inaccessible for those who prefer a warmer sound. It's a great chip for genres with a big sound and lots of instruments, to help expand the soundstage for the music and bring out details in your listening.

The SEM2 offers a more bodied sound than the SEM1. AK DACs tend to be by nature warmer than their ES counterparts, and the AK4497EQ is no different. Still offering plenty of detail the low frequencies are rounder, offering more perceived bass than the SEM1. Mids are warmer, more energetic, and a little more boosted than the SEM1, making guitars sound more in your face. Highs are still detailed, but more rolled off and smoother. The SEM2 is great for genres like classical and jazz, which benefit from a more musical presentation but still retains that sense of detail and intimacy in the performances. Performance-wise, the SEM2 is going to be identical to the SEM1, not making any difference in battery life and overall speed of the SE180 music player from power draw.

The SE180 DAP comes packaged with the SEM1 module, which is equipped with the flagship ESS ES9038PRO DAC chip. These days DAC chips are just a part of the sound signature equation, and one thing that the SE180 boasts that other DAPs can't is a completely separated DAC section from the rest of the machine. This means that the power and RF signals/noise from the main unit is completely blocked by the engineering design of the DAP. Less noise also means a more pure auditory experience. The ES9038PRO is an excellent DAC, providing a surprising amount of detail and clarity to your digital audio. I would say it's on the analytical side of balanced, but not totally inaccessible for those who prefer a warmer sound. It's a great chip for genres with a big sound and lots of instruments, to help expand the soundstage for the music and bring out details in your listening.

The SEM2 offers a more bodied sound than the SEM1. AK DACs tend to be by nature warmer than their ES counterparts, and the AK4497EQ is no different. Still offering plenty of detail the low frequencies are rounder, offering more perceived bass than the SEM1. Mids are warmer, more energetic, and a little more boosted than the SEM1, making guitars sound more in your face. Highs are still detailed, but more rolled off and smoother. The SEM2 is great for genres like classical and jazz, which benefit from a more musical presentation but still retains that sense of detail and intimacy in the performances. Performance-wise, the SEM2 is going to be identical to the SEM1, not making any difference in battery life and overall speed of the SE180 music player from power draw.

Basically, it's a great choice for those wanting a warmer and more bodied sound compared to the SEM1 module. You're gonna get tones closer to the SP2000 from the SEM2, but the dual AK chips won't compete with the Flagship player. Rolled-off top end, better layering, and more defined imaging are just some of the characteristics out of the box. The SEM2 is a smooth listening experience.

The SEM3 is a totally new flavor of sound for the SE180 music player. Equipped with four ES9038Q2M DACs, it's interesting to see that they went with a quad-Q2M chip variant with this module, as there are some notable differences between the PRO and Q2M chips. PRO chips are 8 channels whereas the Q2M chips are only 2 and are more power-efficient. Without getting into specifics of channel architecture and how multi-DAC configurations affect SNR and THD, just know this: there are sonic differences between the PRO and Q2M chips despite both being ESS and designed for the same DAP music player. The most notable difference in A/B testing was with the song "This Is Home" by one of my all-time favs, San Diego-based Switchfoot. With the SEM3, the xylophone bell tones at the beginning of the song are more vibrant, with the new module providing more sizzle on the top-end than the original SEM1. The soundstage is enhanced as well, with the instrumentation having more expanse and depth when compared to the SEM1. Because of this soundstage expansion, the vocals in this track seemed more recessed, but far from being covered up. The SEM1 certainly made the vocals stand out more in the front of the mix, but the SEM3 just allows for more breathing room, with imaging being more precise. Attacks sounded sharper with a tighter bass response on the SEM3 as well, the drums and bass having less rumble, but still very present in the overall sound.

SEM Module Chipsets

SEM1

ES9038PRO (x1)

Balanced, forward-leaning, dynamic, closer soundstage

SEM2

AK4497EQ (x2)

Warm, musical, extension in the low frequencies, better layering, and improved imaging

SEM3

ES9038Q2M (x4)

More analytical, improved depth and imaging, sharper attack, and tighter low end

SEM4

AK4493EQ (x2)

Natural sounding, warm-leaning. A good mix of SEM1 with the SEM2

These changes translated as well to other songs like Across the Universe (Beatles) and Across the Great Divide (Semisonic). The SEM3 provides better soundstage and top-end sizzle than the SEM1, but I would say that the SEM1 provides better energy and overall balance. I think Astell&Kern made a good decision with how they've marketed these removable modules, providing the most balanced option to be packaged with the SE180 music player.

The new SEM4 is designed with another dual DAC configuration with the AK4493SEQ chip. It's a newer chip from Asahi Kasei and the first time it's been implemented in an Astell&Kern product. Like most Asahi Kasei chips, the 4493SEQ runs on the warm side, equipped with their patented AKM Velvet Sound technology, but the real draw here (pun intended) is that it's a low-power consumption chip. The low power draw means that it can still perform at optimum levels while still maintaining low noise and distortion measurements and a wide dynamic range. It also means that the music player can run even longer since the DAC module consumes less power overall, providing about 14 hours of playback - more than any other SEM module for the SE180 DAP. The SEM4 is surprisingly natural sounding at the end of the day - not as warm as the 4497 chip but still providing plenty of body and mid-to-low-end depth. It's almost a mix between the tonality of the SEM1 with some of the warmth from the SEM2. It's a good option for genres like Jazz, Rock, Blues, and Folk, where you want clarity in the performance without sacrificing the musicality and feeling at the same time. At the end of the day, the best SEM module pairing for you is going to be based on your personal listening preferences and what kind of music you like to listen to.

Sound Signature Recap

SEM1

Balanced, forward-leaning, dynamic, closer soundstage

 

Great for: All genres

SEM2

Warm, musical, extension in the low frequencies, better layering, and improved imaging

Great for: Classical, Jazz, EDM, R&B, Metal

SEM3

More analytical, improved depth and imaging, sharper attack, and tighter low end

Great for: Classical, Pop, Alternative, Country

SEM4

Natural sounding, warm-leaning. A good mix of SEM1 with the SEM2

Great for: Jazz, Rock, Blues, Folk    

The Best of Switchfoot
This is Home by Switchfoot
(The Best Of)
Let it Be
Across the Universe by The Beatles (Let It Be Super Deluxe)
The Great Divide
Across the Great Divide by Semisonic (The Great Divide)
Bernstein Century: Copland
Appalachian Spring
by Aaron Copland
(Bernstein Century: Copland)

Features

Interchangeable Modules - With the SE180 DAP, Astell&Kern wanted to expand on the multi-DAC idea that was first introduced with the SE200. Like the SE200, different DACs can be used in one DAP, but for the SE180 they decided on implementing a new system of interchangeable modules. Swap-able cards or modules aren't new, as companies like iBasso have been doing them for years with their DX line of music players, but Astell&Kern is quick to point out that their system is different from the competition. Unlike iBasso, the SE180 is a module-separated product that increases the convenience of connection between the main body of the player and the module. It features an innovative double-locking design that securely connects each component while providing smooth lines that naturally flow without any sense of separateness between the two pieces. By applying different DAC/Amplifier configurations and adjusting the tuning and outputs for each module, the user can choose the most suitable module for their sonic preferences for high-end audio quality.

Open SE180 with SEM cards on table

Modules Double Lock for Ease of Use - The biggest difference between the SE180 and other products that use interchangeable modules is that the SE180 uses a double-locking mechanism rather than screws to fasten the module to the body. The first locking structure attaches the module and the body. The second locking structure informs the user that the module has been securely fastened to the main body. The spring-supported internal connectors of the main body allow reliable audio signal connection and are used to prevent connection failure in case of external shock to the player when on the go.

Astell&Kern Audio Technology Forms the TERATON ALPHA Sound Solution - TERATON ALPHA is AK's ultimate Sound Solution to produce audio playback that is close to the original sound through the audio output interface by use of effective power noise removal, efficient power management, and amplification with minimal distortion. TERATON ALPHA features Astell&Kern's patented technologies, which are the result of tens of thousands of hours of continuous research and development to produce the sound close to the original sound the artist and producer intended.

Next-Generation Advanced AMP Technology - It is extremely difficult to push beyond your previous best. With the SE180, Astell&Kern applied Next Generation AMP technology to push beyond the sound quality others feel is acceptable for Premium Hi-Fi Sound to produce the best sound possible. From the selection of OP-AMP parts to circuit design, board layout, and tuning, everything has been completely redesigned to produce the best sound. It is difficult to improve the Signal-to-Noise Ratio (SNR) while maintaining a high output.

Circuit Separation Structure of Main Body and Module - By physically separating the main body from the All-in-One DAC module, Astell&Kern completely blocks power and RF noise that may occur from the main body. This creates an independent structure that prevents noise from interfering with music playback.

Digital Audio Remaster Technology (SEM4 Only) - The SEM4 features digital audio remaster (DAR) technology — the first time the technology has been applied in an Astell & Kern product. DAR technology is developed to upsample the sample rate of the sound source being played to go beyond the limits of the source format. The high sample rate allows more refined play and offers delicate and analog-like original sound, helping you to enjoy the richness of the original sound, subtle differences in the nuance of the music, and rich sounds at a higher level.

*The DAR function can be turned on and off and you may select it to suit the source sound and your own preferences.

*Max PCM rate 384kHz/DSD256 conversion play is supported, and the files will be converted to and played in the sample rates that fit the source sound.

The Verdict

The SEM module development from Astell&Kern represents one of the best things in the audiophile industry: tailoring your gear to your listening preferences. People don't hear the same, so your audio gear shouldn't sound the same either. Choices are great, and I hope more companies apart from iBasso and Astell&Kern take note.

The SEM2, 3, and 4 provide some great alternative sound signature options to the SEM1 that comes with the SE180 music player from Astell&Kern. The SEM2 is the first to offer an AKM option providing much more warmth and body to your listening experience with a great sounding DAC chip. The SEM3 offers some nice differences from the SEM1, providing more depth, a wider soundstage, more top-end sparkle, and other characteristics that make it a better option for those wanting a more analytical and detailed sound for their music player. The SEM4 is a great middle-of-the-road option between the clarity of the SEM1 and the warmth of the SEM2 - with more neutrality across the board, making it a great option for those who don't want to sacrifice any detail in the name of musicality.

Any SEM module is a good tool to have in the arsenal if you like being portable and having choices for your music. The nice thing about the modules is that they are small enough that you could potentially take all four with you on the road if you wanted to. We said it before: it's good to have options, and Astell&Kern is finally providing them.

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What's in the Box

  • SEM DAC/AMP Module for the SE180 DAP Music Player
  • Plastic Protective Sticker for Top of Module
  • Manual/Paperwork

Videos


Astell&Kern SEM1–4 DAC Modules for SE180 DAP Comparison

Which SEM Module is right for you?


Specifications

SEM2 GENERAL SPECIFICATIONS  
  • Model: PAP12

  • Body Material: Aluminum, Stainless Steel, Polycarbonate

  • Body Color: Moon Silver

  • Sample Rate: PCM : 8kHz ~ 768kHz (8/16/24/32bits per Sample) DSD Native: DSD64(1bit 2.8MHz), Stereo / DSD128(1bit 5.6MHz), Stereo / DSD256(1bit 11.2MHz), Stereo / DSD512(1bit 22.4MHz), Stereo

  • Output: Unbalanced Out (3.5mm), Balanced Out (2.5mm, only 4-pole supported / 4.4mm, only 5-pole supported)

  • Output Level: [Normal Gain] Unbalanced 2Vrms / Balanced 4Vrms (Condition No Load) [High Gain] Unbalanced 3Vrms / Balanced 6Vrms (Condition No Load)

  • DAC: AKM AK4497EQ x2(Dual DAC)

  • Decoding: Support up to 32bit / 768kHz Bit-to-Bit playback

  • Dimensions: 3.03"(77mm)[W] x 2.99"(76mm)[H] x 0.78"(19.9mm)[D]

  • Weight: 3.53oz (100g)

  • Operating Temperature: 3.53oz (100g)

  • Playback Time: about 10.5hours (FLAC, 16bit, 44.1kHz, Vol.50, LCD Off)

Audio Performance
  • Frequency Response: ±0.07dB (Condition : 20Hz~20kHz) Unbalanced / ±0.06dB (Condition : 20Hz~20kHz) Balanced ±0.68dB (Condition : 20Hz~70kHz) Unbalanced / ±0.67dB (Condition : 20Hz~70kHz) Balanced

  • Signal to Noise Ratio: [Normal Gain] 122dB @ 1kHz, Unbalanced / 124dB @ 1kHz, Balanced [High Gain] 125dB @ 1kHz, Unbalanced / 127dB @ 1kHz, Balanced

  • Crosstalk: [Normal Gain] -138dB @ 1kHz, Unbalanced / -145dB @ 1kHz, Balanced [High Gain] -138dB @ 1kHz, Unbalanced / -147dB @ 1kHz, Balanced

  • THD+N: [Normal Gain] 0.0006% @ 1kHz, Unbalanced / 0.0005% @ 1kHz, Balanced [High Gain] 0.0008% @ 1kHz, Unbalanced / 0.0006% @ 1kHz, Balanced

IMD SMPTE: 0.0002%, 800Hz 10kHz (4:1), Unbalanced / 0.0002%, 800Hz 10kHz (4:1), Balanced Output Level: 3.5mm (1ohm) / 2.5mm (1.5ohm) / 4.4mm (1.5ohm)

SEM3 GENERAL SPECIFICATIONS  
  • Model: PAP13

  • Body Material: Aluminum, Stainless Steel, Polycarbonate

  • Body Color: Moon Silver

  • Sample Rate: PCM : 8kHz ~ 768kHz (8/16/24/32bits per Sample) / DSD Native: DSD64(1bit 2.8MHz), Stereo / DSD128(1bit 5.6MHz), Stereo / DSD256(1bit 11.2MHz), Stereo / Native DSD512(1bit 22.4MHz), Stereo

  • Output: Unbalanced Out (3.5mm), Balanced Out (2.5mm, only 4-pole supported / 4.4mm, only 5-pole supported)

  • Output Level: [Normal Gain] Unbalanced 2Vrms / Balanced 4Vrms (Condition No Load) [High Gain] Unbalanced 3Vrms / Balanced 6Vrms (Condition No Load)

  • DAC: ESS ES9038Q2M x 4(QuadDAC)

  • Decoding: Support up to 32bit / 768kHz Bit-to-Bit playback

  • Dimensions: 3.03"(77mm)[W] x 2.99"(76mm)[H] x 0.78"(19.9mm)[D]

  • Weight: 2.82oz (87g)

  • Operating Temperature: 0°C ~ +40°C (32°F ~ 104°F)

  • Playback Time: about 13 hours (FLAC, 16bit, 44.1kHz, Vol.50, LCD Off)

Audio Specifications
  • Frequency Response: ±0.05dB (Condition : 20Hz~20kHz) Unbalanced / ±0.068dB (Condition : 20Hz~20kHz) Balanced / ±0.05dB (Condition : 20Hz~70kHz) Unbalanced / ±0.68dB (Condition : 20Hz~70kHz) Balanced

  • Signal to Noise Ratio: [Normal Gain] 121dB @ 1kHz, Unbalanced / 123dB @ 1kHz, Balanced [High Gain] 124dB @ 1kHz, Unbalanced / 126dB @ 1kHz, Balanced

  • Crosstalk: [Normal Gain] -138dB @ 1kHz, Unbalanced / -143dB @ 1kHz, Balanced [High Gain] -138dB @ 1kHz, Unbalanced / -145dB @ 1kHz, Balanced

  • THD+N: [Normal Gain] 0.0005% @ 1kHz, Unbalanced / 0.0005% @ 1kHz, Balanced [High Gain] 0.0007% @ 1kHz, Unbalanced / 0.0006% @ 1kHz, Balanced

IMD SMPTE: 0.0007%, 800Hz 10kHz (4:1), Unbalanced / 0.0008%, 800Hz 10kHz (4:1), Balanced Output Level: 3.5mm (1ohm) / 2.5mm (1.5ohm) / 4.4mm (1.5ohm)

SEM4 GENERAL SPECIFICATIONS
  • Model: PAP14

  • Body Material: Aluminum, Stainless Steel, Polycarbonate

  • Body Color: Moon Silver

  • Sample Rate: PCM : 8kHz ~ 768kHz (8/16/24/32bits per Sample) / DSD Native: DSD64(1bit 2.8MHz), Stereo / DSD128(1bit 5.6MHz), Stereo / DSD256(1bit 11.2MHz), Stereo / DSD512(1bit 22.4MHz), Stereo

  • Output: Unbalanced Out (3.5mm), Balanced Out (2.5mm, only 4-pole supported / 4.4mm, only 5-pole supported)

  • Output Level: [Normal Gain] Unbalanced 2Vrms / Balanced 4Vrms (Condition No Load) [High Gain] Unbalanced 3Vrms / Balanced 6Vrms (Condition No Load)

  • DAC: AKM AK4493SEQ x2 (Dual DAC)

  • Decoding: Support up to 32bit / 768kHz Bit-to-Bit playback

  • Dimensions: 3.03"(77mm)[W] x 2.99"(76mm)[H] x 0.78"(19.9mm)[D]

  • Weight: 3.17oz (90g)

  • Operating Temperature: 0°C ~ +40°C (32°F ~ 104°F)

  • Playback Time: about 14 hours (FLAC, 16bit, 44.1kHz, Vol.50, LCD Off)

Audio Specifications
  • Frequency Response: ±0.09dB (Condition : 20Hz~20kHz) Unbalanced / ±0.048dB (Condition : 20Hz~20kHz) Balanced / ±0.65dB (Condition : 20Hz~70kHz) Unbalanced / ±0.65dB (Condition : 20Hz~70kHz) Balanced

  • Signal to Noise Ratio: [Normal Gain] 121dB @ 1kHz, Unbalanced / 121dB @ 1kHz, Balanced [High Gain] 125dB @ 1kHz, Unbalanced / 125dB @ 1kHz, Balanced

  • Crosstalk: [Normal Gain] -134dB @ 1kHz, Unbalanced / -138dB @ 1kHz, Balanced [High Gain] -135dB @ 1kHz, Unbalanced / -143dB @ 1kHz, Balanced

  • THD+N: [Normal Gain] 0.0003% @ 1kHz, Unbalanced / 0.0004% @ 1kHz, Balanced [High Gain] 0.0005% @ 1kHz, Unbalanced / 0.0006% @ 1kHz, Balanced

IMD SMPTE: 0.0003%, 800Hz 10kHz (4:1), Unbalanced / 0.0003%, 800Hz 10kHz (4:1), Balanced


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