Astell & Kern AK120 II + ALO Continental Dual Mono Bundle

Astell & Kern

A great value combo deal, consisting of the Astell&Kern AK120-II Digital Audio Player and the ALO Continental Dual Mono Tube Headphone Amplifier!

Colour choice is for amplifier only, the AK120-II only comes in Silver!

  • With the AK120 2nd Generation, we aimed for the perfect harmony of engineering and design. From beginning to end, we re-examined the PCB layout, the form factor, the materials, and the post-manufacturing process.

    Re-examination of the volume wheel’s position.

    We relocated the volume wheel to the top to maximize the space for the battery. We also redesigned the volume wheel for further convenience and easier usability even when you hold the product with both hands.

    Redesign of the volume wheel and guard.

    The AK120 2nd Generation’s volume wheel consists of two parts: the head and the root. The head is the knurled part and control the volume wheel by holding it securely. The root is the base of the volume wheel and wrapped in a guard that’s directly connected to the hardware. This division into two parts enhances the usability and stability of the AK120 2nd Generation, while the distinguished parts also provide further protection for external damage.
  • We added the CS4398 Dual DAC and the balanced output method with sound quality proven through our flagship model. 

    The AK120 2nd Generation provides the weighty sound through the CS4398 Dual DAC and the A-amp, while providing delicate melodies through the balanced output.

    The unbalanced method is the most commonly used basic method which consists of “left and right signals + ground line”. This setup includes a ground line which blocks out external noises from the outside. However, since the ground line cannot block out all of the external noises completely, external noises can be mixed into the signals that are transmitted, which then result in changes to the sound. The longer the signals travel, the more external noises that will be mixed into the sound which is why it is used within a short distance of 1 to 2 meters.

    Unlike the unbalanced method, the balanced method has an additional cold signal to compliment the hot signal which reduces the external noises.

    We got familiarized with the DSD format because of the AK120. However, because of the limited hardware functionality, the AK120 could only support DSD up to 2.8MHz with PCM conversion / downsampling to 88.1kHz. Thanks to the advanced hardware functionality and the DSD to PCM software, we can now provide playback support of DSD upto 5.6MHz.

    The AK120 2nd Generation includes the USB DAC feature.

    Connect the AK120 2nd Generation to a PC or Mac and use it as a USB DAC that also supports DSD. With Dual DAC and the USB DAC feature, enjoy a richer resolution in sound that goes beyond the limitations of the sound card installed in your computer.

    With the AK120 2nd Generation, you can now skip the complicated process of searching for music files, connecting to the PC, and downloading the files to the player. Simply connect the AK120 2nd Generation to your music collection on your computer in the same network to download and/or stream music!
    • Model:AK120 II
    • Body Color:Stone Silver
    • Display:3.31inch WVGA (480 x 800) AMOLED Touchscreen
    • Supported Audio Formats:WAV, FLAC, WMA, MP3, OGG, APE(Normal, High, Fast), AAC, ALAC, AIFF, DFF, DSF
    • Sample rate:FLAC, WAV, ALAC, AIFF : 8kHz ~ 192kHz (8/16/24bits per Sample) / DSD : DSD64 (1bit 2.8MHz), Stereo / DSD128 (1bit 5.6MHz), Stereo
    • Output Level:  Unbalance 2.1Vrms / Balance 2.3Vrms (Condition No Load)
    • DAC:Cirrus Logic CS4398 x2 (Dual DAC)
    • Decoding:Support up to 24bit/192kHz Bit to Bit Decoding
    • Input:  USB Micro-B input (for charging & data transfer (PC & MAC)
    • Outputs:PHONES (3.5mm) / Optical Out (3.5mm) / Balanced Out (2.5mm, only 4-pole supported)
    • Wi-Fi:802.11 b/g/n (2.4GHz)
    • Bluetooth:V4.0
    • Dimensions:2.16 ”(55 mm) [W] x 4.64 ”(118 mm) [H] x 0.58 ”(14.9 mm) [D]
    • Weight:  6.24 oz (177 g)
    • Frequency Response:±0.023dB (Condition: 20Hz~20kHz) Unbalance & Balance
    • Signal to Noise Ratio:  116dB @ 1kHz, Unbalance / 117dB @ 1kHz, Balance
    • Crosstalk:130dB @ 1kHz, Unbalance / 135dB @ 1kHz, Balance
    • THD+N:0.0007% @ 1kHz, Unbalance / 0.0005% @ 1kHz, Balance
    • IMD SMPTE:0.0004% 800Hz 10kHz(4:1) Unbalance / 0.0003% 800Hz 10kHz(4:1) Balance
    • Output Impedance:Balanced out 2.5mm (1ohm) / PHONES 3.5mm (2ohm)
    • Clock Jitter: 50ps (Typ)
    • Capacity:3,250mAh 3.7V Li-Polymer Battery
    • Supported OS:Windows XP, Windows 7,8 (32/64bit), MAC OS X 10.7 
  • Pure Power
    Each stage of the CDM has its own dedicated linear voltage regulator. This means the internal voltage of each stage is independent. This minimizes the sharing of differing internal voltages across each stage of amplification and the digital to analog converter.

    Linear voltage regulators are used because they produce a cleaner voltage rail than typical switching regulators. Because they do not use a switching waveform, linear regulators have lower output noise. Lower output noise is better for clean amplification. And in high fidelity amplification it is critical.

    Dedicated linear voltage regulators to each stage of amplification provides optimally clean power. Less crosstalk between the stages and better isolation of the analog and digital sections.

    The Touch of Tubes

    At the center of The Continental Dual Mono are a pair of New-Old Stock 6111 Vacuum Tubes. Each tube is individually soldered to a custom PCB. This provides mechanical isolation of each tube, insulating them from unwanted microphonics. It also provides a quick and easy solution for tube-rolling.

  • Directly following the volume potentiometer, the dual 6111 vacuum tubes provide the current gain (ie tube “buffer”) to the amplification. This provides a clean, strong and dynamic signal to the headphone output stage at a lower output impedance.

    Running in Class A, the Dual Mono implementation of the vacuum tubes provides improved stereo separation and an expanded soundstage. This is because of lower levels of crosstalk achieved between Right and Left channels. The tubes are auto-biased so there is no need for any time consuming manual biasing.

    Microphonics are a unique challenge when introducing vacuum tubes to a portable amplifier. The design of the tube circuit in The Continental Dual Mono minimizes the inherent microphonic tendencies of the tubes. Utilizing the tubes as a buffer, handling the current gain and not the voltage gain reduces microphonics. Mechanical isolation of each tube and the component layout of the PCB further assist eliminating any distracting microphonics.

    While the tubes are user replaceable, the vacuum tubes as implemented can easily be expected to provide 5+ years of reliable operation.

    Supremely Solid (State)

    The Continental Dual Mono is a “tube/SS hybrid” amplifier. It delivers the low output impedance, tight bass and sonic precision of a solid-stage amp, but with the added midrange richness, expanded soundstage and spaciousness of a tube amp.

    The Class AB solid-state output stage is designed laid out with short path lengths and a low part count. Only the highest quality components are used in The Continental Dual Mono. The voltage regulators, decoupling capacitors and resistors all have tight specifications. Rated to operate at wider temperature ranges and for extended cycle life.

    Digital Dynamo

    The Wolfson WM8741 DAC chip occupies the heart of The Continental Dual Mono’s digital section. We selected this chip after extensive examination of all available reference DAC chips. The WM8741 has exceptional signal to noise ratio and extended dynamic range. It also provides low noise, low distortion and superior linearity. The Wolfson provides high resolution DSD and PCM playback and offers musically compelling digital filters.

    WM8741’s minimal phase digital filter is more natural sounding because it has no ‘pre-ringing’ of its impulse response. Just as a piano doesn’t produce sound before a key is pressed, the minimal phase filter doesn’t ‘pre-ring’ its impulse response.

    The power feed to the digital section is turned OFF when the USB cable is unplugged. When the DAC is active, the internal Li-Ion battery and linear voltage regulators provide the power. The noisy 5V rail from the USB is not used for any part of the power. This means less grain to the sound and no digital harshness.
    For lowest amounts of jitter and cleanest digital to analog conversion we used a high quality clock IC in The Continental Dual Mono. For both PC and MAC computers, PCM 16/24 bit - with these sample rates (kHz) of 44.1, 48, 88.2, 96, 176.4, 192, as well as DSD64 are all supported. MACs require the driver provided for DSD playback. PCs require a driver for both PCM and DSD playback.

    Mobile devices also play well with The Continental Dual Mono. Android devices can pair with the DAC using a micro USB OTG cable and the ALSA driver. Apple iDevices can pair with the DAC using an Apple Camera Connection Kit and micro-USB to USB-A cable.
    The front panel lights provide you with quick access to the DAC’s sample rate. Red = 44.1 / 48kHz, Green = 88.2 / 96kHz, Blue = 176.4 / 192kHz, White = DSD64

    Big Beautiful Battery

    The Panasonic 18650 batteries are combined into a 3 cell pack to provide clean, reliable power to The Continental Dual Mono. The 3-cells are in series to deliver the voltage the tubes demand.

    We selected the this battery because it has a high cycle life, approximately 1000 cycles. It also provides short circuit and overcharge protection. It is also safely user replaceable. So when you reach the end of the batteries life, you can swap in a new one and keep the music going.
    Using a high quality battery to power The Continental Dual Mono makes the music come alive. Beyond the low noise floor you’ll discover tight controlled bass, natural midrange and a grain-free extended top-end. The clean power is immediately appreciable in the dynamic sound from the amplifier.

    Audio Line Out

    The Continental Dual Mono has a true “Line Out” on the rear panel. This is a fixed 2Vrms analog output signal. This signal is from the output of the DAC’s analog output stage. It is tapped before going through the volume control or headphone output stage.

    We included this feature to showcase this exceptional DAC. It is intended to drive a preamp, integrated amp, another headphone amp, such as our Studio Six headphone amplifier. Please note that the Line Out is not intended to drive headphones directly, but instead offers you flexibility in using the DAC with your other components.

    Awesome by Design

    Our new enclosure design is inspired by our daily use of our products. Machined markings resist wear and the minimal icons keep you focused on the music. The Gorilla Glass window lets the tubes shine without exposing them to the elements. Expanded vents running along the sides of the CNC’d aluminium enclosure keep The Continental Dual Mono breathing as the tubes heat the interior.

  • Power Output Single Ended
    80mW into 32 ohms
    95mW into 50 ohms
    75mW into 150 ohms
    60mW into 300 ohms

    Power Output Balanced
    125mW into 32 ohms
    145mW into 50 ohms
    110mW into 150 ohms
    95mW into 300 ohms