Astell&Kern ACRO CA1000: What exactly is this? Very, very good is one thing…
A form of this review is forthcoming on eCoustics as well.
We have had very good luck with Astell& Kern (A&K) of late. They were kind enough to send us the Kann Max fresh from the Munich High End Show, and Will had the privilege of getting the first review out for the excellent SP3000. The ACRO CA1000 came as a result of the SP3000 shipping back to the west coast for CanJam SoCal. I was not sure how this device fit into the A&K line up…until I heard it for the first time.
Astell & Kern is known for making some of the very best DAP’s out and are a favorite of Senior Headphone Editor Jennings. I concur with the excellent sound, and our reviews of the Kann Max make note, stating, “do you really need anything else besides this?” After spending over 200 hours listening to the CA1000, I would say yes. Yes, you do. Marketed as a carriable headphone amplifier, the CA1000 is so much more; that it could easily replace many of the devices you have in your home already. With Bluetooth (5.0), you can easily stream from your favorite apps such as Qobuz and Tidal. Tidal comes as a “service” already loaded. Qobuz and Spotify can be downloaded to the service folder as well. With other available input and output options, the A&K is politely defined as a headphone amplifier, to me.
Specs:
| Model | ACRO CA1000 |
| Body Color | Moon Silver |
| Body Material | Aluminum |
| Display | 4.1-inch 720 x 1280 Touch screen |
| Supported Audio Formats | WAV, FLAC, WMA, MP3, OGG, APE, AAC, ALAC, AIFF, DFF, DSF, MQA |
| Sample Rate | PCM: 8kHz – 384kHz (8/16/24/32-bits per Sample) DSD Native: DSD64 (1-bit, 2.8MHz), Stereo / DSD128 (1-bit, 5.6MHz), Stereo / DSD256 (1-bit, 11.2MHz), Stereo / DSD512 (1-bit, 22.4MHz), Stereo |
| Output Level – Headphone Out | [Low] Unbalanced 2Vrms / Balanced 4Vrms (Condition No Load) [Mid] Unbalanced 4Vrms / Balanced 8Vrms (Condition No Load) [High] Unbalanced 6Vrms / Balanced 12Vrms (Condition No Load) [Super] Unbalanced 8Vrms / Balanced 15Vrms (Condition No Load) |
| Output Level – RCA Out | 2Vrms (Condition No Load) |
| CPU | Quad-Core |
| DAC | ESS ES9068AS x 4 (Quad-DAC) |
| Decoding | Support up to 32-bit / 384kHz Bit-to-Bit Playback |
| Headphone Outputs | Unbalanced (3.5mm, 6.35mm) / Balanced (2.5mm, 4.4mm) |
| Analog Inputs / Outputs | RCA (Stereo pair) x 1 |
| Digital Inputs | Coaxial x 1, Optical x 1, USB (Type-C) x 1 |
| Digital Outputs | Optical (3.5mm) x 1, USB (Type-C) x 1 |
| Wi-Fi | 802.11 a/b/g/n/ac (2.4/5GHz) |
| Bluetooth | V5.0 (A2DP, AVRCP, Qualcomm® aptX™ HD, LDAC) |
| Dimensions | 4.12” (104.9mm) [W] x 1.77” (45mm) [H] x 5.85” (148.8mm) [D] |
| Weight | About 32.41oz (919g) |
| Feature Enhancements | Firmware upgrade supported (OTA) |
| Operating Temperature | 0°C – +40°C (32°F – 104°F) |
Audio Specifications
| Frequency Response | Condition 20Hz~20kHz: ±0.024dB Unbalanced / ±0.018dB Balanced / ±0.048dB RCA Condition 20Hz~70kHz: ±0.059dB Unbalanced / ±0.056dB Balanced / ±0.048dB RCA |
| Signal to Noise Ratio | 107dB @ 1kHz, Unbalanced / 115dB @ 1kHz, Balanced 119dB @ 1kHz, RCA |
| Crosstalk | -105dB @ 1kHz, Unbalanced / -124dB @ 1kHz, Balanced -121dB @ 1kHz, RCA |
| THD+N | 0.005% @ 1kHz, Unbalanced / 0.002% @ 1kHz, Balanced 0.0004% @ 1kHz, RCA |
| IMD SMPTE | 0.0008%, 800Hz 10kHz (4:1) Unbalanced / 0.0004%, 800Hz 10kHz (4:1) Balanced 0.0003%, 800Hz 10kHz (4:1) RCA |
| Output Impedance | 3.5mm, 6.35mm (1ohm) / 2.5mm, 4.4mm (2ohm), RCA (2ohm) |
Clock Source
| Clock Jitter | 25ps (Typ) |
| Reference Clock Jitter | 70ps |
Storage Capacity
| Built-In Memory | 256GB [NAND] |
| External Memory | microSD (Max. 1TB) x 1 |
Battery
| Capacity | 8,400mAh 3.8V Li-Polymer Battery |
| Playback Time | About 10.5 hours (Standard: FLAC, 16-bit/44.1kHz, Unbalanced, Vol. 40, LCD off, Low Gain) |
| Charge Time | About 2.5 hours – 9V/3A PD2.0 Fast Charging About 7 hours – (5V/2A General Charging) |
Operating System
| Supported OS | Windows 7, 8, 10 (32/64 bit), MAC OS X 10.7 and up |
The Skinny
A&K devices are known for their heft and quality construction as trademarks, and the CA1000 is no different. While considered carriable, I would find a sturdy carrying case to protect it. As for that quality construction, the South Korean device is impeccable to me. Made from a solid aluminum block, the device looks the part, with smart angular surfaces, much like their DAP’s. From pictures, you really do not know what the device looks like, until you get it in hand. What looked like a DAP sitting on a charging port, is actually the interactive touchscreen, mimicking an A&K DAP. Running a base Linux OS, the system is functional, if a bit spartan. But we really came for the music.
On the front are four headphone jacks including all of the commonly used ones: 6.35mm se, 3.5mm se, 4.4bal, & 2.5bal moving left to right. The 6.35 and 4.4 are lined in gold color making the device elegantly simple in silver and gold. Spaced equidistant on top are four buttons, which control (L to R): power, rewind, play/pause, and forward. Each may be used when the screen is off as well. A large knob on the right is the volume wheel, with bronze colored accent rings on the inside much like a 24” wheel. The knob has a knobby pattern to it for easy use and control. One thing of note, is that one click, actually means one click of the volume. No matter how I tried, it still worked in a 1 to 1 ratio; unlike many less expensive volume wheels & knobs. Quality.
The top front is also canted towards the user for easier access to the buttons. Not once did I have any issue with the controls.
Moving to the back, you have the multitude of connectivity options. Set inward on a black plexi-board are (L to R) RCA output, RCA input, Coax in, and optical in forming the top row. Underneath are easily accessible slots for the micro-SD card, charge port (USB-C), and Data/Audio (USB-C). Even though the unit runs on battery, it is nice to have complete access to all the features on the back without any hinderance. Labels are easily read as well. The sides have parallel lines of decreasing spacing as you move from top to bottom. A nice accented touch, which also allows for a no-slip grip of the unit when you pick it up. No screws are visible, and I would assume they are available under the four rubber feet, which came mounted already.
Accessories included are limited to the charging cable, and an instruction manual along with the warranty card and two extra screen protectors. I took the liberty of mounting one of the three, and it was quite easy to do. With outputs ranging from 2Vrms to 15Vrms depending upon the source and headphone jack used, there is plenty of power to run your devices.
Calling this carriable is an applaudable way of A&K saying, “Yes you can, but protect it for the heft may burden you a bit.” I found it fit comfortably into my backpack, in the box; taking up about twice the space of the Sennheiser Momentum4 with which it shared the space.
Operating System
Coming with A&K’s familial Linux OS, do not expect a lot. Meant to operate the unit and stay out of the way, it simply worked. No issues whatsoever in delay or stuttering were had in the entirety of time I used the CA1000. Basic in operation, the terminology did take a bit of getting used to. I familiarized myself by reading other reviews, and the website having no trouble once locations were found for basic operating principals.
There is a tan circle, with a leftward facing arrow in it, which acts as the control for accessing the previous menu screen whether that be running Tidal or music from the SD card. A swipe to the right brings up the ACRO’s sub-functions ranging from songs to device settings and the aforementioned “service” function for streaming services; dependent upon what app you are in. Tidal came preloaded and adding Qobuz was as easy as going through the same Services screen. I had no issues either with downloading or playing the apps.
While in an app, the functions menu can be accessed by swiping from top to bottom, much like Android DAP’s as well. Two sliding screens worth of information can be garnered from that dropdown menu ranging from WiFi and BT connectivity to source input. The second set of buttons (accessed by swiping left) allow a bit of personalization from EQ, replay gain and all of the device’s settings. AK Connect is turned on from here as well. Used to “help” download” items from the web if needed. Touching the “Settings” button takes you to the settings screen with minimal delay. All functions can be accessed here, including toggling on the “Roon Ready” feature. While Linux is basic in operation, the plethora of useful features make it a very logical, easily used OS.
Each time the AMP is changed, volume defaults back to a reasonable 40/150 limit. This is done so one does not have a large increase when moving from say High to Super. A nice feature, and volume is then easily changed using the scroll wheel mentioned above.
Functions
With as many functions available to the user as a “regular” DAP, the learning curve is straightforward as well. Additional features can turn the CA1000 into a very good streamer as well. Hooking the unit to my budget Rotel RA932 and Mission MS-50 speakers (for another article) allowed me to play Tidal or Qobuz without any issues. While much more expensive than most streamers, the sound quality alone might very well be worth it.
As for those other functions, sometimes basic OS is indeed worth it for simplicities sake.
Sound
Having several test units available across the spectrum, I utilized the full character of the A&K from Bluetooth and the wonderful UW Drops, to the Campfire Audio Supermoon Custom & Focal Celestee for headphones/IEMs. As mentioned, I also hooked the ACRO to my budget used Rotel/KEF system for the streaming capabilities. As luck would have it, I also had a pair of the excellent Klipsch The Sixes delivered and hooked the pair together through BT without issue.
Pairing with the UE Drops Custom was easy and within a minute or two of power on, I had Kenny Burrell streaming from Tidal. Having heard the Kann Max recently, I had an appreciation for the typical A&K sound. Known for the immense amount of detail wrought through their DAP’s, Astell & Kern are well versed in presenting a crisp sound signature. The only DAP, which comes close for me in the ability to generate details of this manner and magnitude is my equally excellent Questyle QP2R. While others place their signature pattern on the sound, A&K (along with Questyle) try to present the music as if it were coming off the mastering tape. I appreciate the ability to come across as cleanly as possible, allowing the user to experience what the sound engineer might hear as well.
The Drops have excellent bass tendencies, while the mids seem to take the show. Detail from Monty Alexander’s “Spunky” come across with character and authority. But not overbearing decisiveness. Some DAP’s put a price on notes such as piano, giving authority, but with a certain presence to it that seems out of character. The CA1000 presents these notes without any inside influence. The air between notes is remarkable for the black background, and an anticipatory feeling you might get waiting for the next to come along. “Tres Palabras” from Burrell & Hawkins is a marvelous piece with which to gauge resolution and presence. You know Coleman’s sensuous solo is coming, but the anticipatory set of waiting draws you in with the A&K/UE combination. Then the sax kicks in and you get it.
As wonderful as the Drops were, the CA1000 started to really shine when the Focal Celestee (& Stellia) was plugged in. With excellent fit in the closed-back design, the Focal was allowed to show its mettle through the A&K. Taut bass that ran not too deep set the tone followed by sumptuous mids emanating from Celia Cruz’ “La Vida Es Un Carnaval.” A sensuous line permeates the song, and the duo showed through with superb mids. Succinct, tight and clear her vocals came across like you were front row center. But along with excellent clarity, there was enough definition to give the song real weight; without becoming shouty as a front row seat could become. Tight control continued into the treble range with staccato notes giving air with aplomb, but also tight enough to keep the South American soul to the song. Loretta Lynn’s (RIP) “Portland, Oregon;” played next, and that crispness of sound kept the melodic almost psychedelic song moving with excellent transients. When her vocals come in, you get the juxtaposition of west-coast psychedelic sound combined with country that only she could get away with.
The ACRO CA1000 can also fit into a home streaming system easily as well. Using the RCA connectivity, the A&K seamlessly joined my budget Rotel RA-932 & Mission MS-50 system. Purchased for another set of reviews, this budget system will grace my office up north along with a Denon DP-45F turntable. For a budget system, much worse could be had. Entering the A&K into the mix with Tidal streaming, the sound was easily as good as anything I had put through so far. Monty Alexander’s “Night Mist Blues” showed that the Mission speakers could sound much larger than their diminutive size offered. I will also admit that I had a fancy for these when paired with the excellent Denon component system in which they were paired decades ago. And yes, the CA1000 cost over 2.5 times what I spent on the system. Regardless, the Astell & Kern easily streamed Tidal and Qobuz through the system making for a very worthy addition.
Pairing the ACRO with my go to Bluetooth speakers, the equally good Klipsch The Sixes, the sound coming out made The Sixes sound better. Klipsch are known for their tweeter treatment, which can become a bit harsh. The A&K allowed those high notes to shine through, but without the brutal nature, which can happen sometimes. To say the Astell & Kern is carriable makes its most valid point in this situation. It was at this point, where I realized the value of the name.
Conclusion
Astell & Kern are legendary for the sound emanating from within their impeccably made and designed DAP’s. There is no question that they are the marker to hit regarding quality and sound along with very competent functionality. Many aspire to beat that mark and as such use the company as their target, often in advertising as well.
Where does this high priced carriable headphone amplifier fit in today’s market then? As witnessed above, pretty much wherever it wants. With multi-connectivity options, the CA1000 is about the most versatile amplifier to come our way. Others have the connectivity options, but not the streaming capability from within; relying upon an outside source to provide the means. The A&K provides the user with everything they need for a carriable use on commutes, and it should hold a hallowed spot on one’s desk. Then once you are back home, it can enter your home system seamlessly, pretty much guaranteed to make that system better.
The ease of which the CA1000 can be used along with the functionality provided makes this one of the absolute easiest headphone amplifiers on the market to integrate into your system, completely. This is a spectacular unit, and I have thoroughly enjoyed inserting it into many options, including the home system mentioned above. When one thinks that this could easily bring an audiophile quality into your home streaming system as well as a superb headphone amplifier, it is quite easy to see that A&K hit their mark square. It will be a real shame that this one has to go back, for I will miss it and the functionality massively.
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