Astell&Kern ACRO L1000 Desktop Headphone Amplifier
- Intriguing design
- Volume knob to end all volume knobs
- Detailed, powerful sound through any headphone
I remember hearing a news story about a South Korean government program to develop design skills within the country. Why outsource that when they can do it just as well? It’s hard to find evidence of the actual government initiative at this point – maybe if I was searching in Korean. But, it’s easy to find evidence of the result, Astell&Kern has been cranking out beautifully designed portable music players for six years, with their first step into the stationary (ie, non-portable) hifi realm their design momentum has carried them straight out of the box, landing with the beautiful, totemic ACRO L1000 DAC, Headphone Amp and Amp.
Dual High-End AK4490 DACs
Multiple headphone jacks:
2.5, 3.5mm or 6.3mm jack, or 4-pole XLR balanced
Three Digital Filter choices:
Neutral, Bass emphasis or High Gain
4.44” (113mm) [W] x 6.29” (160mm) [H] x 4.43” (112.75”) [D]
32.45 oz (921g)
USB Micro-B (PC/MAC)
3.5mm, 6.5mm, 4 pin balanced XLR
L/R Binding Posts
Astell&Kern, DAC, Headphone Amp, Headphones, Headphone AMP Review 2019
I must list the two amps separately because there are indeed two amps inside the beautiful, all aluminum, enclosure. For the headphones there is a class A-B amp driving through any one of four possible connections. For the speakers, a class-D amp drives passive speakers via traditional speaker binding posts. Those speaker posts, while as beautiful as any, do push the limits of the appeal of the overall design in my opinion. Connect your speakers via banana plugs and you’ve got a two pair of two-inch protrusions, add the power connector and USB (micro) input and there are six wires connected. I think the general idea is that the L1000 would be positioned such that you aren’t looking at the back. That might be the case for you, it might not. If you are the CEO of your own multi-national corporation (and who isn’t, really?), the people coming into your office might end up seeing the back of the L1000 as they approach your extra-large modern desk. But you’re the CEO so they have to like it.
Back inside the unit for a sec, the DAC is implemented with a pair of the latest from Asahi Kasei Microdevices (AKM) – the AK4490. A pair of DAC chips is used to create a truly balanced output. Beware devices which have balanced connections but are actually all single ended except for that connection. You might be paying extra for nothing in those cases. I am quite a fan of AKM DACs. I think there is a default-thought out there that ESS is the king, but I find there is a darkness to the ESS solutions that AKM does not have. More in the ‘in use’ section below.
Ok, back on the outside, the on/off button is neatly embedded along the upper-left edge, just to the left of that glorious knob. It is easy to inadvertently press it while moving the L1000, it’s just natural to grab it there if you must pick it up, or if you want to hold it steady to insert or remove headphones. That’s not as bad as it might seem however because turning the L1000 off requires holding that button down for about 5 seconds. Turn-on is instant. I heard only the faintest pop, if any, through headphones or speakers when turning on or off.
A small round button down low on the left-hand side selects between three filter options. The documentation for the High Gain mode is unclear. Given that one of the other modes adds bass, you would not be blamed for thinking that High Gain added something to the treble end. But the description says that this option supplies more power output. This doesn’t seem like something that is in the realm of a filter of any kind, all the more so a digital filter being applied well before the (power) amp. I had to check with Jason Henriques of Astell&Kern on that one. He confirmed that it is a filter (not power) option – slower roll off than the standard filter.
The cables supplied with the L1000 are for connecting to other Astell&Kern products or an Android phone. The connection on the L1000 itself is USB micro-B. I went on a little USB cable odyssey – starting with what I had on hand, the cable that came with a Kindle Fire, then I bought a Pangea. At the same time, I bought an inexpensive USB Type B to micro-B adapter which let me try some other cables: a seemingly nice but unbranded USB cable with ferrite-cores on each end, a Purple Plus USB from Analysis Plus and finally Blue Heaven from Nordost. Each seemed like a step up from the previous, but I didn’t circle back for a real cable evaluation at any point. It was enough to play with the various headphones I had on hand. For those that are interested, the Purple Plus has a slightly warm sound compared to the all the others. The Blue Heaven imparts more detail but said detail is not at all harsh through the L1000. I can recommend either of those cables but if you are on a budget, the Pangea will do you right and doesn’t require an adapter. I may have been pushing the envelope in terms of weight and torque that should be applied to the USB micro slot in the L1000 with the adapter.
Ok let me just start by saying that reviews of audio products are written on a computer. Stay with me now. If the audio product is plugged into said computer, and produces awesome music, it might end up taking some extra time to write said review. That was my experience with the ACRO L1000. This very paragraph took 4 minutes 55 seconds, the length of the third track, ‘Strength’ on Lida Husik’s latest album ‘MotherOceanMorning’.
And once that was done, I had to listen to a few more tracks and then switch headphones and do it again. So hard.
I did most of my listening with Beyerdynamic T1 v2’s plugged into the balanced connection on the back of the L1000. I also found myself addicted to my old Grado 325i’s through the L1000 – a new experience with those cans. And I managed to borrow a pair of Focal Clear’s for a short time.. oh my. All listening was with JRiver Media Center v22 which makes it easy to select between different audio devices and their drivers. For the L1000 I used the supplied ASIO driver. A WASAPI version is also supplied.
About that small button for the filter options – each of the options is subtle enough to not be annoying but trying to select among them might be. There’s not a lot of difference. I eventually tried just leaving it in one mode or another without thinking about it. I found that I enjoyed the High Gain and Neutral options equally, with no inclination to switch to something else. When using Bass Boost mode, I was inclined to switch. Not because there was too much bass but because I kept wondering if there was. None of the modes were fatiguing. I stayed with the neutral selection most of the time.
The round, articulated side of the L1000 did get pleasingly warm after a period of spirited listening, more noticeable if the ambient temp was also warm – not always the case in my house. As I am from a time long ago, I have a tower computer underneath my desk. The USB connection to the L1000 was plugged into there and then placed on top. I ended up putting a cork coaster underneath the amp to isolate from the fan vibration in the case. I’m willing to stipulate that the small difference I heard was in my head. If the L1000 is on your desk, this won’t be an issue.
That big ol’ volume knob takes a lot of turning for small volume change. Eleven, yes eleven lights along the side of the knob let you know where you are on the scale. (There is a 12th LED at the bottom end of the scale but it indicates the filter choice.) It takes about three complete turns to go from zero to eleven for volume. I gotta say, I appreciated the design of the L1000 plenty before I counted and re-counted the eleven lights. There’s a lot going wrong in the world today but if a bit of supreme silliness from an American movie made in 1984 is still ringing around the world some 24 years later, I have hope. If it was happenstance and Nigel Tufnel’s custom amp was not the inspiration, well it is for me. The feel of the knob is heavy, there is a resistance to the turning. I did most of my listening at the seven or eight-light position. I would have been afraid to turn it up to eleven.
Ok how to describe the sound of the L1000? True to what you might know about class A-B amps, it is powerful. Any of the cans I tried were driven with authority. More so than any of the other headphone amps I have on hand except the exceedingly expensive 430HA from Simaudio. The delightful sound of the AKM DAC chips is well implemented here. There is a bounce and lightness (not brightness) to the renderings. Instruments are well separated, so much so that I never even had a thought as to whether any blurring was happening. Usually I find myself wondering what it is that is not-quite-right when listening to digitally sourced music and typically the answer is that somewhere, on some level, some of the instruments or voices are blending together.
That didn’t happen with the L1000. Extension on both ends is supreme. There is a real you-are-there quality to cymbals and the snap of snare drums. If you are familiar with amplifier topologies you would ask if there was crossover distortion or fatigue from the A-B layout of the L1000. Not that I could tell. I did compare to my old Centrance DACmini which is a pure class-A amp (and uses an older AKM DAC chip), there was a smoothness through the midrange with the Centrance but at a cost of roll-off on both ends. With the L1000 though, authority, it knows what the music should sound like and that’s what you get.
To compare to an ESS DAC I put my Benchmark DAC 2 HGC on the desktop and did some switching back and forth. I gotta say, I was totally prepared to find the more expensive Benchmark beating the Astell&Kern but that was not the case. I prefer the L1000 by a country mile. Compared to the L1000 the DAC 2 had a bit of a slow pace and the aforementioned darkness. I was using the balanced connection from the L1000 which the DAC 2 doesn’t support so I switched to single ended from the L1000, no change in my conclusion. I thought it might be the headphone-amp combination, so I switched from the Beyer’s to the Grados. Still I prefer the L1000. Listening to the MP3 of Bat For Lashes’ “The Bride”, a harp accompanies Natasha Khan’s soaring soprano as this beautiful song cycle gets underway, the open top end of the L1000 lets it soar and the harp strings sparkle. With the Benchmark, both of those are muted a bit by comparison and I found that I wasn’t keen to keep listening. With the L1000 I wanted to find more music to play. Once again, the typing of this paragraph is being delayed while I listen to more of “The Bride” through the Grados. I do this knowing that my Beyer’s would sound a little better but it’s not worth changing at this point.
With the L1000 these old Grados are like a two-seater roadster, light and responsive and fun. And it wasn’t just mid-range, the thumping bass on Eleanor Friedberger’s “Stare at the Sun” (from Personal Record) was distinct from the other instruments in a way that I haven’t heard on headphones before. Don’t overdo it with a two-seater roadster though, switching to Dum Dum Girls’ cover of “There is a Light that Never Goes Out”, the Grados seemed to break up, couldn’t really deliver the loud, heavily strummed guitars. (Beyer’s did fine.)
I managed to borrow some Focal Clear’s from Portland’s favorite hifi store, Stereotypes Audio. These ‘phones are indeed the bomb as has been reported elsewhere. I did a lot of switching back and forth between the Focals and my Beyerdynamics. Note that matching volume while switching headphones is no easy task – especially in this case as the difference in impedance is substantial. So, you can take my summation with a grain of salt but like a lot of other folks, these Focals get the best of most anything else I’ve (we’ve) heard. These Beyers though are being overlooked in all the hub-bub. The Beyers go for an intimate listening experience. Focal Clears on the other hand are just that. Clear. Clarity out the yin-yang. This means that many of my favorite aspects of music reproduction were served up by the Focals in much larger portions: details, instrument separation, tonal characteristics like chunky bass guitar were mesmerizing with the L1000 and Focal Clears. It was certainly a case of not knowing what I was missing with the Beyers and interestingly, not missing it too much when the Focals had to go back to the store. The T1 v2s present a more coherent whole with a mix that lands on the ears as though it were coming from a full-size system. Not that there was a soundstage anywhere other than between my ears, it’s just that the instruments all seemed to be in the correct relationship to each other. The Focals emphasize everything, all the time.
And then there’s comfort. The Focal Clears are within a hair’s breadth of crossing the line into ‘strapping a pair of speakers to your head’. They are big, on the heavy side and I found them distinctly uncomfortable for the first few songs. It might be that my large head stretched out the metal headband over this time (don’t tell Stereotypes!). That headband makes a wonderful crinkly sound when you handle these ‘phones by the way. It sounds like… gear.
I wanted to see what the L1000 could do with MP3s of varying quality. I have some bootleg recordings of Mazzy Star live in Chicago in 1993: “The Black Sessions”. Looking at the audio properties according to Windows: “Encoder Settings – Constant Bit Rate 320kbs (Insane).” Hee hee. I guess that opinionated engineer is saying that it makes no sense to use the MP3 format at all if you aren’t going to compress at least a little. It would be nice if someone could compress away the tape-hiss but otherwise this is actually a lovely recording as bootlegs go. The L1000 and Beyer’s presented the intimacy of Mazzy Star and I was caught up listening for a long time again.
Listening to the MP3 download that came with the vinyl of Jenny Lewis’s “The Voyager” – the L1000 wasn’t able to completely undo the shortcomings on these files. Having listened to the vinyl version many times I can hear that the digitized version has an annoyingly flat soundstage and that fatiguing quality.
The download accompanying Garbage’s latest record “Strange Little Birds” is MP3 at 192 kbps, 16 bit word depth according to the audio information reported by Windows. But the song titles indicate a somewhat richer origin, the first track on the record is “Sometimes.” The title in the download: 01_Sometimes_24bit_96kHz_MFiT_Final_Master_3.1.16.
JRiver reported the sample rate as 48 kHz. There was no mention of the bit depth that I could see but the output to the ACRO L1000 DAC was 32 bit, 48 kHz. So, unclear but something more than the normal MP3. It did sound richer than the 44.1/16 material I have on hand, the L1000 was happy to have some extra bits to dig into but if this higher res file were something I had to pay for, I would only do that for my faves.
Is there anything better than the L1000? Not too much in my house apparently but maybe the 5x more expensive Simaudio 430HA? On Radiohead’s “Amnesic”, which has some especially dense tracks, there was more intimacy and deep black backgrounds with the 430HA as compared to the L1000. On the other hand, voices and the midrange, such as the piano on “Pyramid Song”, are more prominent when presented by the L1000. Who’s to say which is right? In most cases, I found the commanding power of the Sim to be clearly superior, but you’d better have a big desk. With further listening, every now and then I would hear some things through the L1000 that I didn’t hear on the (ESS DAC equipped) Sim: One example, playing the album download Flac (44.1/16) of Radiohead’s “2+2=5” from “Hail to the Thief” the L1000 imparted a sweetness to Mr Yorke’s voice that I did not hear through the Sim.
And then there is that whole other amp in the L1000 that none of the above DACs can compete with. The L1000 is neatly supplied with a separate amp for driving passive speakers. I heartily applaud this choice, there are hundreds of excellent passive speakers (including some from Astell&Kern) that will fit on your desk that are a better and more versatile option than amplified speakers. I resurrected a pair of Radio Shack Minimus 7’s (yes I’m a nerd) for the task. These are actually still highly regarded speakers but probably don’t support the full range that the L1000 could deliver. The experience was in no way equal to the headphone experiences I had but I still found music engaging and voices (from internet radio sources) clear and compelling.
I think the most remarkable thing about the ASTELL&KERN L1000 is not its stunning looks, it’s that it didn’t seem to matter which headphone I was using, I didn’t want to stop listening. If the design and ergonomics are to your liking, the sound will be as well. Highly recommended.
- Beautiful design. Truly balanced DAC implementation that makes music in headphones and your head.
- A mute button would be handy sometimes, it takes a lot of turns to go from eleven to zero with the oversized volume knob. Also, MQA decoding is all the rage (or hype anyway), it is coming soon on other Astell&Kern products but not the L1000.