Astell&Kern Acro CA1000: an incredibly versatile headphone amplifier

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Mis à jour le 16 May 2022.

With more and more people working from home, desktop headphone amplifiers have become a must-have item. These compact models are becoming an increasingly important addition to traditional hi-fi systems. The Korean manufacturer Astell&Kern wants to bring its expertise to this sector with the new Astell&Kern Acro CA1000. One of a kind, this portable model is also a USB DAC, a network player and a pre-amplifier, offering a very comprehensive and ultra versatile hi-fi solution. Designed according to the same requirements as the Korean manufacturer’s best DAPs, the Astell&Kern Acro CA1000 adopts four 32-bit/384kHz, DSD512 and MQA 8x compatible DACs. Its amplification section can power the majority of headphones thanks to an output of 15V RMS and 4 outputs: a 3.5mm jack, a 6.35mm jack, a 2.5mm jack and a 4.4mm jack. Finally, its battery makes it easy to move from one room to another. Can this latest generation headphone amplifier with retractable screen excel in the many areas it promises to cover? Will it be up to the standard of the DAP specialist’s other products?

The Astell&Kern Acro CA1000 is an ultra versatile model that serves as a headphone amplifier, a USB DAC, a network player, a hi-fi source and a preamplifier. 

Astell&Kern Acro CA1000: packaging & accessories

Inside its sleek and stylish packaging, the Astell&Kern Acro CA1000 headphone amplifier is properly protected by thick packing foam. It comes with two tempered glass screen protectors, a user guide and a USB-C to USB-A cable for charging and the USB DAC mode.

The Astell&Kern Acro CA1000 headphone amplifier comes with a quick start guide, screen protectors, as well as a USB-C to USB-A cable for charging and the USB DAC mode.

Astell&Kern Acro CA1000: presentation

Design 

The Astell&Kern Acro CA1000 headphone amplifier is in keeping with the South Korean manufacturer’s line of DAPs. It uses the same aesthetic codes, with a particularly attractive chassis crafted from a single block of aluminum. The angles of the upper part recall the geometrical shapes of the brand’s portable DAPs, such as the Astell&Kern A&norma SR25, Astell&Kern KANN Alpha and Astell&Kern A&Futura SE180.

The Astell&Kern Acro CA1000 headphone amplifier looks like an Astell&Kern DAP on steroids. It has the same design, with an aluminum chassis and sharp angles.

The top of this chassis features controls to turn the device on and off, start and pause playback and change tracks (next track and previous track). These features are accompanied by a large grooved volume control knob located on the right side. Directly inspired by the prestigious Astell&Kern DAPs, this potentiometer ensures smooth and very precise adjustment of the volume over more than 150 levels.

The large potentiometer on the right side of the Astell&Kern Acro CA1000 headphone amp ensures smooth and precise volume control over 150 levels.

To get as close as possible to the experience offered by the brand’s DAPs, the Astell&Kern Acro CA1000 headphone amplifier is easily controlled via its retractable touch screen. It can be inclined up to about 80°. It takes a bit of force to lift the screen from its base. However, this means that the screen can be used without it tipping back. A mechanism that automatically raises the screen when the device is turned on would have been simpler, while reinforcing the charm and prestige of this Astell&Kern headphone amplifier. A gadget that was probably scrapped to preserve the compact format and avoid the introduction of an element that could cause interference.

The Astell&Kern Acro CA1000 headphone amp, DAC and network player has a touch screen that can be raised by about 80°.

The Astell&Kern Acro CA1000 headphone amp’s screen is intuitive to use, but its size of only 4.1″ stops the experience from being really convincing. It is a far cry from the large screens offered by the latest generation of smartphones. Reading the information and using the numeric keypad requires good eyesight and finesse. Moreover, the operating system associated with a seemingly weak processor does not allow the screen to provide smooth navigation. The system sometimes struggles, with more or less significant delays when loading applications and browsing through the music library. Fortunately, once the music starts, you can control the playback with the device’s physical controls, which are much more ergonomic.

The Astell&Kern Acro CA1000 headphone amp’s display is intuitive to use, but could be made larger for more comfortable viewing.

Quadruple ESS DAC

The Astell&Kern CA1000 headphone amp has a balanced architecture designed around four ESS ES9068AS DACs. This reference chip from ESS Technology can also be found in the brand’s high-end DAPs, including the Astell&Kern KANN Alpha and the Astell&Kern A&ultima SP2000T. The use of four DACs ensures separate conversion of the left and right channels to limit interference, optimize the signal-to-noise ratio of 115 dB and reduce distortion to only 0.005% in unbalanced mode and 0.002% in balanced mode. With two DACs per channel, the Astell&Kern Acro CA1000 can convert most audio formats. It performs bit-perfect playback of PCM streams up to 32-bit/384kHz resolution and supports DSD files up to DSD512 as well as MQA (8x). The Astell&Kern Acro CA1000 DAC is therefore capable of playing your entire music library and decoding all formats offered by Hi-Res streaming services, including Tidal and Qobuz.

The Astell&Kern CA1000 headphone amp features four ESS ES9068AS DACs to separately convert the left and right channels and optimize both the dynamics and the signal-to-noise ratio.

Triple amplifier

The Astell&Kern CA1000’s amplification stage uses three separate chips: two chips mounted in a double mono configuration for the balanced outputs, and one chip for the unbalanced outputs. This amplification is paired with exclusive Teraton Alpha technology that optimizes the synergy between the various components, in particular with the power supply. The latter’s reinforced shielding limits interference and disturbances. This design allows the Astell&Kern Acro CA1000 headphone amplifier to deliver up to 15 Vrms in balanced and 8 Vrms in unbalanced. Four adjustable gain settings are available to match the characteristics of your headphones or IEMs. This flexibility is reflected in the wide choice of outputs: 3.5mm jack, 6.35mm jack, 2.5mm jack and 4.4mm jack.

With a high power output and four headphone outputs (3.5mm jack, 6.35mm jack, 2.5mm jack and 4.4mm jack), the Astell&Kern CA1000 can easily power any pair of headphones or IEMs.

Connectors

In addition to its 4 headphone outputs, the Astell&Kern CA1000 headphone amplifier features a wide range of connectors to pair many sources. It features an optical input and a coaxial input to connect a CD player, a TV or a network player, for example. Two USB ports are also available. The first is used to charge the battery and the second allows you to use the Astell&Kern CA1000 as a USB DAC with a compatible computer or smartphone. Lastly, it is possible to connect an analog source such as a pre-amplified turntable to the RCA stereo input. The Astell&Kern CA1000 can be added to an existing system thanks to a fixed or variable level RCA output. It can then be used as a DAC and network player with a hi-fi amp or as a pre-amplifier with a power amp.

Thanks to a wide range of connectors, the Astell&Kern CA1000 can be used with analog and digital sources, and can be used as a source or pre-amplifier in an existing hi-fi system.

HD Streaming

The Astell&Kern Acro CA1000 desktop headphone amp adopts a proprietary operating system with the same interface as many of the brand’s DAPs. The homepage displays the music library where you can browse music by albums, songs, artists, genres, playlists or folders. Music can be stored in the internal memory of the headphone amp, but also on a micro SD card or on the local network. 

By swiping from the top to the bottom of the screen, it is possible to quickly modify certain settings, including WiFi, Bluetooth, the equalizer, the USB DAC mode, the screen brightness and the output level. Swiping from left to right lets you access more precise settings, such as the gain and filters. On the same page, you can download or access your favorite online streaming services, notably Spotify, Qobuz, Deezer and Tidal.

Connected via WiFi, the Astell&Kern Acro CA1000 headphone amplifier can access music shared over the local network, as well as many online music services such as Qobuz and Tidal.

LDAC and aptX HD Bluetooth

In addition to the headphone outputs, the Astell&Kern Acro CA1000 USB DAC can also stream all your music to a pair of Bluetooth headphones or Bluetooth IEMs via Bluetooth. To do so, the A&K Acro CA10000 is equipped with a Bluetooth 5.0 controller that is compatible with the majority of codecs, including aptX HD and LDAC. The transmission rate is therefore optimized with compatible receivers, for better sound quality. Note that this Bluetooth module is bi-directional, allowing you to stream music to the A&K Acro CA1000 headphone amplifier from any Bluetooth source: smartphone, tablet, DAP, computer, etc.

In addition to a wide range of connectors, the Astell&kern Acro CA1000 can also receive and stream music in aptX HD and LDAC Bluetooth.

USB power supply and battery

At 10.4cm long, 14.8cm deep and 4.5cm high with the screen folded, the Astell&Kern Acro CA1000 headphone amplifier is relatively compact. Its format associated with a design with an exemplary finish makes it ideal to take place on a desk, next to the computer, on a bedside table, or even on the hi-fi cabinet in the living room. Thanks to its rechargeable battery, it can be easily transported from one room to another in the house. This makes it perfect for freely enjoying music throughout the house, without having to install a system in each room. Outside, it can also be used in the garden or on the patio. This flexibility is one of the biggest advantages of this Astell&Kern headphone amplifier. However, the Astell&Kern Acro CA1000’s weight (almost a kilo) makes it mainly suitable for home use. For portable use, a DAP is more convenient.

Thanks to its integrated and rechargeable battery, the Astell&Kern Acro CA1000 can work in total autonomy for more than 10h30.

Battery powered, the Astell&Kern Acro CA1000 headphone amp offers up to 10h30 of autonomy, allowing you to enjoy music all day. For longer listening sessions, the A&K Acro CA1000 can also be powered via USB when connected to the port of a computer, hi-fi equipment or directly to a USB mains adapter (not included).

Astell&Kern Acro CA1000: key specifications

  • Quadruple ESS DAC
  • 32-bit/384kHz, DSD and MQA compatible
  • Streaming services
  • Analog and digital inputs
  • Balanced and unbalanced headphone outputs
  • Battery or mains power
  • Battery life: 10h30
  • Retractable touch screen
  • Dimensions (WxHxD): 104.9mm x 45 x 148.8mm
  • Weight: 919g

Astell&Kern Acro CA1000: listening conditions

For our review, we connected the Astell&Kern Acro CA1000 headphone amplifier to the Meze Empyrean Elite and Audeze LCD-5 open-back headphones, as well as the Meze Liric closed-back headphones. We tested the Astell&Kern Acro CA1000 with Hi-Res and DLNA tracks stored on the local network, as well as music from Qobuz and Tidal to enjoy high resolution streaming. We also connected several physical sources, including a Teac CD transport via the coaxial input to review the A&K Acro CA1000’s hi-fi DAC performance. Last but not least, we also used the Astell&Kern Acro CA1000 as a source to enjoy streaming services with our hi-fi system. To do so, the RCA output was connected to a Pathos New Classic One MKIII amplifier using AudioQuest Red River cables.

The Astell&Kern Acro CA1000 headphone amplifier and high-end Planar Magnetic Audeze LCD-5 headphones.

Astell&Kern Acro CA1000: listening impressions

The heritage of Astell&Kern’s digital audio players was embodied in the sound signature of the Astell&Kern Acro CA1000 headphone amp. The music had room to breathe and expressed itself with agility through a vast soundstage. The spaciousness was remarkable, with plenty of depth, width and height. The spatial image benefited from a beautiful texture which provided a true holographic reproduction. Each instrument, from the smallest triangle in the background to the grand piano, was embodied with conviction and naturalness. The sound message was remarkably detailed.

With the Meze Empyrean Elite headphones and Astell&Kern Acro CA1000 headphone amplifier, the music had room to breathe and was very spacious.

As usual, the South Korean manufacturer impressed us with the transparency of the reproduction. The background was a void, leaving complete silence between two musical breaths. No murmurs or background noise interfered with the music, even with very sensitive headphones. An acoustic purity that benefited the details, whose perception was always perfect. From the plucking of acoustic guitar strings to vocals, everything was audible and no recording flaw escaped the acuity of the Astell&Kern Acro CA1000. 

The Astell&Kern Acro CA1000 displayed excellent tonal accuracy, with a consistent reproduction and perfect spectral balance. Each frequency range was full of nuance and details. The well-structured lows were perfectly controlled and went a lot deeper than some of the manufacturer’s DAPs, like the KANN Alpha. The top end of the spectrum was beautifully clear, allowing the highs to soar. The precision of the details was excellent across a wide frequency range, reproduced with great linearity. The slightest notes were audible and expertly reproduced.

The Astell&Kern Acro CA1000 headphone amp displayed great tonal accuracy, with a consistent reproduction and perfect spectral balance.

Astell&Kern Acro CA1000: compared to…

iFi Audio Pro iCAN Signature: sold for €2,249, this iFi Audio headphone amplifier has the advantage of dual amplification: either transistors or tubes. In vacuum tube mode, the iFi Audio Pro iCAN Signature offers a warmer, fuller and smoother reproduction. The mids are even richer, for the benefit of even more captivating performances with jazz and acoustic music. The iFi Audio Pro iCAN Signature is less versatile, however, with purely analog connectors. Moreover, the absence of a network connection does not allow it to be used as a network player or to access music shared over the local network, unlike the Astell&Kern Acro CA1000. Finally, the A&K Acro CA1000 has the advantage of being battery operated, making it easy to use throughout the house. 

Astell&Kern A&ultima SP2000T: available at the same price as the A&K Acro CA1000, the Astell&Kern A&ultima SP2000T is a serious alternative for enjoying a truly portable system. This A&K DAP offers a very similar sound signature, notably due to the use of four ES9068AS DACs, identical to those of the Astell&Kern Acro CA1000. However, the mids are a little richer and smoother with the SP2000T thanks to its tube amplification. The Astell&Kern Acro CA1000 does, however, take advantage of a stronger amplification section to provide even more robust bass and a more dynamic sound. Finally, it is more versatile with support for streaming services, access to music shared over the local network and extended connectivity. For home use only, the Astell&Kern Acro CA1000 is the most flexible. But if you also plan to listen to music on the go, then the A&K A&ultima SP2000T is a more suitable solution. 

Astell&Kern Acro CA1000: who is it for?

The Astell&Kern Acro CA1000 headphone amp is halfway in between a DAP and a sedentary headphone amplifier. It maintains the connectivity and power of the latter for the connection of physical sources, while bringing the versatility of portable music players for the playback of music stored locally, shared over the network in DLNA or played from streaming services. The rechargeable battery offers a real advantage over traditional headphone amplifiers for enjoying music more freely from one room to another in the house. The Astell&Kern Acro CA1000 is most often used on the desk next to the computer, but it can also be taken to the coffee table in the living room, the bedside table or the patio to enjoy music in the sun.

The Astell&Kern Acro CA1000 headphone amp is ideally placed on a desk to enjoy music while working, but can also be carried from one room to another thanks to its rechargeable battery.

Astell&Kern Acro CA1000: conclusion 

With the Astell&Kern Acro CA1000, the South Korean manufacturer combines the best of its DAPs in an even more versatile piece of equipment designed for home use. With transparency, musicality and accurate nuances as its guiding principles, the Astell&Kern Acro CA1000 inherits the great musicality that made the brand a success. However, it also suffers from the in-house operating system which needs to be smoother and more responsive to provide a truly user-friendly experience with the touch screen. The latter could also be larger to guarantee better readability, although it is undeniably more advantageous than a classic headphone amp. These few shortcomings are forgotten as soon as the playback starts. Apart from that, the Astell&Kern Acro CA1000 excels in every aspect, whether it is used as a headphone amp, an audio DAC or a network player. Finally, the rechargeable battery offers a major advantage to enjoy this versatility in any room of the house.

We liked:

  • The compact and discreet format
  • The wide range of connectors
  • The transparent sound
  • The spaciousness and width of the soundstage

We would have liked:

  • A larger touch screen
  • A more responsive operating system

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