Astell&Kern A&ultima SP2000T Digital Audio Player review

Astell&Kern, South Korean maker of brilliantly-designed Digital Audio Players (a.k.a “DAPs”) has brought a compelling new entrant into the high-end portable audio world with the release of the latest model in their A&ultima flagship line of products, the new $3,599 Astell&Kern A&ultima SP2000T Digital Audio Player.

While Astell&Kern’s products are already renowned for squeezing-in a host of innovations with each new release, the new SP2000T ups the ante with a range of “firsts” that build on the already-impressive spec-sheet of the Astell&Kern A&ultima SP2000 Digital Audio Player, from which the SP2000T takes its sonic inspiration.

One DAP to rule them all? 

I’ve always had a DAP in my listening arsenal - and why not? When you spend a good chunk of your life outside, on the road, or away on travel, there’s no reason why you shouldn’t be able to treat yo’ self to first-rate sound wherever you happen to find yourself. But, when I’m at home I generally tend to stick to my desktop gear for listening. I often ask myself whether a DAP could replace several other devices in my audio system - after all, they are a) a source, through on-board files and/or streaming; b) have a DAC built-in, and c) amplify headphones. However, many DAPs that I’ve spent time with either don’t have enough juice under the hood to tango with full-sized headphones, have a sub-par user experience, or are missing one or two key features that hold them back from being good enough to replace a bunch of other devices. 

I’m also an avid tube listener at home having built a few tube amps of my own, and I like to spend time mixing up my listening experience between solid state and tubes. Are tubes better? I won’t delve into that potentially controversial topic here, but I will say that listening to tubes is different (in a good way). And so when I first got the heads-up that I’d be taking a look at the new A&ultimate SP2000T I did get very interested when I learned what Astell&Kern has packed under the hood in their latest angular-looking portable device. “If it’s what I think it is,” I said to myself at the time, “then this could get very interesting indeed”. 

With all of Astell&Kern’s smarts plus a couple of new party tricks onboard in the new SP2000T, then this could well be the most complete portable device going around - and potentially a complete headphone rig as well. 

A&ultima SP2000T - what’s new? 

  • KORG Nutube Vacuum Tube Amplifier 

  • New “Triple Amp System” with “OP”, “HYBRID” and “TUBE” modes

  • 2.5 mm, 3.5 mm and 4.4 mm Output Jacks

  • 4 x ESS ES9068AS QUAD-DAC, for Balanced, Ultra Detailed Sound

  • TERATON ALPHA, Astell&Kern's Ultimate Sound Solution

  • Replay Gain Function to Maintain Consistent Playback Levels between Tracks

  • Dual-Band Wi-fi Support for Uninterrupted Wireless Connection and Improved Compatibility

  • Internal Mechanical Design to Minimise Noise

T for tube 

Yes, you read that first feature correctly. Astell&Kern says that the “T” in SP2000 represents a number of important attributes that they’ve baked into their new DAP, including:

  • “True - The SP2000T inherits the SP2000’s true-sound philosophy”
  • “Timeless - Timeless Value”
  • “Triple - Triple Amp System”

  • However, it’s the last “T” that truly sets the SP2000T apart - “Tube - Vintage Vacuum Tube Amplifier”. You might have seen fancy amplifiers with glowing glass bulbs sticking out of them before and wondered what the big deal is. Well, before the invention of the transistor back in 1947, tubes were the only way to control the flow of current and amplify an audio signal to create sound. The transistor is a far smaller, cheaper and (arguably) better way to do this job which is why they found their way into most audio products from the second half of the 20th Century onward. 

    However, many audio lovers insist that tubes create a better sound that is usually described as “vintage warmth”. Distortion is generally considered a Bad Thing when it comes to audio performance, but tubes add a level of harmonic distortion that many people find preferable as it adds a kind of euphonic warmth - “good distortion”, if you will. Many audiophiles (myself included) like to have a separate tube setup to be able to be able to change things up between the clarity, cleanliness and power of a solid-state amplifier, and the more laid-back, warm and fuzzy vibes that only a tube can impart. Things can start to get expensive when you take into consideration the need to acquire tubes which do have a limited life-span (usually about 10,000 hours), not to mention the costs of building a separate rig. Plus, those fancy glass tubes ain’t exactly convenient when it comes to portability - tubes have, until recently, been a strictly “at home” proposition. 

    Astell&Kern thought it was high-time to give tube fans a taste of vintage tube warmth on-the-go, and so have equipped their brand-new A&ultima SP2000T with a dual-triode KORG Nutube 6P1 (pictured below) to give listeners the ability to switch between either solid state and tube amplification with the press of a button, or to mix things up with a little bit of both. The KORG Nutube has an anode grid filament which works in the same way as a classic triode vacuum tube to deliver a classic rich tube character, and yet is far smaller, and draws on much less power. It also promises far more longevity than your Grandfather’s tube, with Astell&Kern explaining that you should expect around 30,000 hours of reliable playback from the KORG Nutube - that’s about three and a half years of back-to-back listening. 

    A&ultima SP2000T "Triple Amp System" 

    The SP2000T gives you the ability to change-up the flavour of your sound thanks to Astell&Kern’s new “Triple Amp System”. Listeners can switch between three different amp modes: “OP AMP”, “HYBRID” or “TUBE” with the press of a menu button/ Or, you can add a dollop of both by choosing between five different levels of OP AMP/TUBE integration in HYBRID mode through a rotary control panel on-screen. 

    The “OP AMP” mode gives you access to the same solid-state amplification technology that Astell&Kern employs across their portable player range and is designed to offer extreme clarity and precision, for a dynamic and detailed listening experience. Portable listeners can finally get a flavour of old-school vintage vibes without having to be tethered to an old-school vintage amp in “TUBE” mode, which is designed to give a uniquely warm, musical sense to your tubes. “HYBRID” mode splits the difference between both modes, and gives you the ability to tailor your sound with your preferred mix of polished clarity, and old-school warmth. 

    Tubes can often be a noisy and frustrating experience - the lightest bump can cause a “TING!” sound to run through your headphones or speakers, and so Astell&Kern has gone to great lengths to ensure that no microphonic noises are present in your listening experience. The KORG Nutube amp module has been separated from the SP2000T’s PCB with flexible silicone covers, and has also been magnetically “floated” from the rest of the circuitry to avoid noise and vibrations. 

    Further to this, pure silver “Shield Cans” have been built into the chassis of the SP2000T to block electronic noise and interference, so that the listener can enjoy an immersive listening experience free from unwanted noise. 

    Analogue power, multiple connections

    The SP2000T generously sports three different connections on its top panel for use with a wide range of popular headphone and IEM cable terminations. The single-ended unbalanced 3.5mm jack has a maximum voltage of 3.0Vrms, and the 2.5mm and 4.4mm balanced connections each push out a healthy 6.0Vrms which promises to be helpful when partnering with full-size headphones. 

    The output impedance on the single-ended and balanced outputs is 1 ohm and 1.5 ohms respectively, meaning that there’s unlikely to be any influence on the frequency-response of lower-impedance IEMs - I didn’t hear any notable difference between single-ended and balanced with my 10 ohm CIEMs save that there was noticeably more power available via the balanced outputs, which is no surprise. 

    A&ultima SP2000T digital prowess

    The SP2000T features not one, but four of ESS’s flagship ES9068AS two-channel DAC chips - the first time Astell&Kern has used this layout in one of their portable devices. Two of each chip are used in the left/right audio channel paths to ensure the SP2000T has uncompromised digital performance, to ultimately result in a more realistic and immersive listening experience. 

    Unsurprisingly, the SP2000T supports an exhaustive list of hi-res file types and is also capable of decoding the proprietary MQA format (take note: Tidal listeners). Standard PCM files up to 32-bit/384kHz are supported, along with DSD up to DSD512 (1-bit/22.4mHz), and when listening to PCM you’re able to switch between three different DAC filters: Linear Phase Fast Roll-Off; Minimum Phase Slow Roll-Off; and Hybrid Fast Roll-Off. 

    A&ultima SP2000T wireless performance 

    In addition to being able to play files saved on the device natively via either a MicroSD card (>1TB) or its internal memory (256GB), the SP2000T boasts dual-band wifi for connection to both 2.4 and 5GHz networks. Once I had connected the SP2000T to my home wifi I was prompted to perform a firmware update, and then went about downloading my hi-res streaming service of choice, Qobuz, from the handful of app options provided within the SP2000T’s re-skinned Android operating system. Users can “side-load” other apps into the SP2000T using Astell&Kern’s “Open APK” system, which offers up more choices in the future than your standard audio playback apps that are offered. 

    The SP2000T’s wifi performance is reasonably good - I didn’t experience any troubles with 192kHz hi-res files over Qobuz within a room or two’s distance from my router, but it does tend to drop away noticeably with a couple of walls in between the DAP and your wifi source. One welcome feature that I appreciated is the addition of “AK File Drop”, which allows you to drag-and-drop files from your Mac/PC straight over to the SP2000T wirelessly through an FTP program. You’ll need to download a dedicated program to do so, such as “Cyberduck” on Mac, but once up and running it works great - especially when you only have two provided USB connections on your Mac! 

    Rounding out the SP2000T’s wireless capabilities is its ability to work as a “two way” Bluetooth device - that is, it can either work as a Bluetooth source and send music to your wireless headphones, for example; or work as a Bluetooth receiver. The latter feature which Astell&Kern call “BT Sink” is interesting as it opens up interesting use cases such as being able to stream from your smartphone to the SP2000T, while using wired headphones - a godsend if you don’t have a headphone jack on your phone. I tested BT Sink a couple of times with my Pixel 6 and it worked flawlessly - no complaints here. The SP2000T is also compatible with the latest higher-res Bluetooth codecs including aptX HD and LDAC, meaning that it’ll be transmitting or receiving with the greatest possible fidelity if you feel like going “cord-free”. 

    A&ultima SP2000T design & build

    An Astell&Kern DAP simply wouldn’t be an Astell&Kern DAP unless it featured an asymmetrical design, an abstract use of straight edges, and gives off wholly “different” vibes - you know you’re looking at something both special and capable. The SP2000T is no different here - while it may not have the same “bling” finish of some of its A&ultima stablemates, Astell&Kern have opted for a more subdued black finish here. There’s no getting around the fact that the SP2000T is a large portable player. It has the same footprint as your average smartphone with at least twice the thickness - all that good stuff inside needs to fit in somehow, right? While at 309 grams it is technically still pocketable, it’s probably better used in a transportable fashion - that is, stored in your bag or luggage and brought out when you feel like some opulent mobile listening. 

    The SP2000T feels rather substantial in the hand - one-handed operation and quick access to the key buttons is possible, but smaller-handed audiophile might need to use two hands to operate it carefully. Heft and footprint aside, the SP2000T feels like a work of industrial art. It feels incredibly well made - the machined aluminium chassis feels strong enough to be used as a landscaping tool, yet the matte finish feels wonderful in the hand. The abstract interplay of the straight edges around the outside of the SP2000T catch ambient light and shade alternately when it’s moved around, making it an eye-catching and conversation-worthy device. 

    The signature focal point on the SP2000T’s exterior is definitely the window on the back panel of the device. It features an LED strip that changes colours according to either the bit-rate of the music being played, or which amp mode is being used (the user can select either). The red default colour that signifies either “OP AMP” mode or a standard 16-bit signal has a real “KITT” vibe from Knight Rider (or perhaps a Cylon from Battlestar Galactica if that’s more your jam) - it looks super cool, but with it facing rearwards you’re probably not going to be looking at it that often. 

    Core functionality of the SP2000T is managed by the four external physical controls: the power/standby button that turns the device on and off and also turns the screen on and off during operation; the three parallel track rewind, play/pause, and track advance buttons on the top left-hand side of the device which are extremely tactile, non-wobbly and easy-to-use; and lastly the excellent volume-wheel. Astell&Kern always pays attention to the volume knob on their devices, knowing that it’s the one thing you’re going to be interacting most with on your device, and it’s no exception here. The SP2000T’s knurled knob is machined from a single piece of aluminium and has a nice tactile “click” to it that makes it extremely accurate, and pleasing to use. 

    The screen has been bumped-up to full-HD specs on the SP2000T with the 5-inch touchscreen panel packing-in 441 pixels per inch and a 1920 x 1080 resolution. It’s bright, crisp, and makes album artwork look amazing. You can actually use the SP2000T to watch video services like Youtube through the “Services” app menu, if you felt so inclined. It works fine, but I like to keep my music devices just that - music devices. 

    After using the SP2000T for a good week or so I did say to myself that I should probably look at getting a protective case for it - with a device this nice (and expensive), you want to keep it that way). After a quick read online I was somewhat embarrassed to read that there was actually one in the SP2000T’s box which I opened once, pulled the device out of, and didn’t look again. The orange-coloured leather case certainly offsets the all-black vibes of the SP2000T and gives you far more confidence when placing it down on hard surfaces - it’s a very welcome inclusion. Some clear protective films for the screen is provided with the SP2000T, along with a USB data and charging cable for connection to the USB-c connection on the bottom panel of the SP2000T next the slot to mount a microSD card. 

    It would be remiss of me not to mention the absolutely stunning wooden display/storage box that the SP2000T arrives in. It's an extremely appropriate storage solution befitting a DAP of this calibre, and it looks absolutely terrific. You certainly won't be hiding this one in your bottom drawer. 

    A&ultima SP2000T user experience

    Operating the device will be immediately familiar for anyone who’s spent time with an Astell&Kern device before. The SP2000T uses the same re-skinned version of Android as the other players in the Astell&Kern line-up and is easily navigable via the touchscreen interface. Key device playback features are accessed via a drop-down menu from the “A” logo in the top-left corner of the screen, and key device settings and managed via dragging down menu options from the top of the screen. I did appreciate that the SP2000T’s screen can be “woken up” via simply double-tapping the display - it’s handy when the top power button isn’t easily reachable. A hidden “home” button at the bottom of the screen and a floating “back” button round out the navigation tools at your disposal - anyone who’s used a smartphone will be up and running in a minute or two. The user interface isn’t quite as snappy as your average 2022-model smartphone, but its generally smooth, intuitive and more than up to the task of managing music playback. 

    The SP2000T features a new setting for an Astell&Kern device called “ReplayGain”. It works by automatically levelling the volume of different tracks so that there is no audible jump up or down in volume. I tried using it for a while, and didn’t notice any noticeable change in volume between tracks, so I guess it must have been working (right?). 

    In addition to being able to tinker with your sound via the Triple Amp System, SP2000T owners can tailor their sound via a fairly comprehensive EQ function. Individual frequency bands can be raised and lowered in the main EQ settings function, but those looking to get a bit more precise can create a full parametric EQ profile for their headphones and IEMs, allowing for finite control of gain level and Q value for each part of the frequency band. 

    As a Roon user I was super glad to see that the SP2000T is a “Roon Ready” device. With the SP2000T connected to the same wifi as my Roon Core, all it takes to get the two paired-up is to switch on “Roon Ready” in settings, adding the SP2000T as your output device in Roon, and it’s ready to accept a lossless stream driven from the interface on your computer - giving you access to your local library, plus all the streaming libraries and digital tinkering tools that Roon has to offer. 

    Astell&Kern claims a reasonable 9 hours of battery life from the 4,200mAh 3.8V Li-Polymer Battery, albeit it under very specific conditions: FLAC, 16bit/44.1kHz, Unbalance, Volume 50, LCD Off, LED On, OP AMP Mode. I didn’t exactly run a torture test under these conditions, and I also liked to switch around modes and headphones with each listening session with the SP2000T. I don’t think I got quite near the 9 hour mark as advertised, but I could confidently take it with me for a day’s worth of mixed listening around my work schedule. 

    With regards to one of the main features of the SP2000T in the “Triple Amp System”, it really is quite as simple as tapping a button to cycle between the three amp functions. At first I envisaged needing a lengthy delay for the tube to “warm up”, but there is about a half-second delay between each mode - you can cycle between them continuously. I must note that I did experience some occasional “hiss” that sounded like some sort of electronic interference when using the SP2000T in Tube mode only, and then, it was only when streaming via wifi - it wasn’t hugely noticeable and did depend where abouts I was situated with regards to other devices. 

    Listening to the A&ultima SP2000T

    Regardless of the amp mode chosen, the SP2000T lives up to the high expectations that Astell&Kern has set with their A&ultima range - from my first listen, it was clear I had a luxurious-sounding, technically brilliant device in my hands that oozes class. Starting things off with some extremely capable IEMs in the form of the 64 Audio U18s Universal In-Ear Earphones and a 16-bit/44.1 WAV recording of Radiohead’s “OKNOTOK” 20th anniversary release of “OK Computer”, the SP2000T presented an extremely black background - I know it might sound weird to talk about what it doesn’t do, but not all players are able to contrast the full details and dynamics of a recording if there’s a hissing or artifacts present that remind you that you’re listening to a recording on a small device. No, that’s definitely not the case here. The bass notes, drum hits and amplified reverb of the electric guitar parts in “Airbag” were able to bounce out of that inky background in a vividly engaging way that simply dragged me in to the recording. 

    Tonally, the SP2000T gave me the impression after a few more tracks that it’s a smooth, natural-sounding player without any errant deviations in any part of the frequency band. There’s detail in spades, and I can confidently say that that the SP2000T/18s combination gave me a closer look into “Paranoid Android” than I’ve ever taken before. What was really impressive about the detail that the SP2000T serves-up is the crunchy attack that it has with the leading edge of notes. This makes the hit of an acoustic guitar string, the texture of a bass note, or the start of a vocal note sound extremely well-defined and makes you feel like you’re listening to something real

    I will say initially that the three amp modes are more alike than they are different, and require close listening to determine their differences. And yet, they still each offer an interestingly-nuanced take on the SP2000T’s abilities that does become more evident with longer listening. “OP AMP” mode provides the most detailed, transparent look into a recording. It also feels like it has the most space and definition between notes, with a noticeably quicker transition between bass notes in particular. I’ll use a completely non-musical analogy to describe what it’s like switching over to “TUBE” to hear the maximum difference between the three modes. It’s a bit like having a large gulp of red wine and sitting back in a nice chair - while you’re certainly nowhere near drunk, you’re just feeling a little more laid back. Separate notes are brought back in a fraction, and the soundstage becomes more smoothed-over. The highest octave becomes a little less lively, and a little more relaxed. Those crunchy leading edges of bass notes become a little less taut, and instead receive a little more heft and warmth. 

    It really is nice to be able to switch between a more “lean in”, acutely-detailed take on a piece of music and then opt for a more “lean back and chill out” perspective on it - all by simply engaging tube mode on the SP2000T. I can envisage listeners choosing between amp modes depending on mood, time of day, and of course - what headphones they’re listening to. Leaner-sounding headphones and IEMs such as the Grado GR10e In Ear Headphones benefit from a little tube “seasoning”, whereas darker-sounding dynamic driver IEMs including the Final Audio E5000 In Ear Headphones tend to shine more with the added clarity and focus that “OP AMP” mode offers.  

    “HYBRID” mode doesn’t have a particularly different sonic character per se, but as you’d expect brings a little bit of both solid state and tube timbres to bear. As I mentioned earlier, there are 5 different levels of “HYBRID” available on tap in the SP2000T which allow you to add incrementally more or less levels of “tubey” character to the sound. I’m kind of an “all or nothing” sort of guy, so I generally found myself switching between “OP AMP” and “TUBE” mode for maximum effect, or to best suit the headphones I was using. 

    Speaking of headphones, the SP2000T sounds absolutely great with full-sized cans. I didn’t have any crazy hard-to-drive headphones lying around during my time with the SP2000T, but it performed absolutely brilliantly with every headphone I through at it. The 300 ohm Sennheiser HD600 Open Back Headphones didn’t need more than 60/150 when driven by the balanced output to get loud, and present a super dynamic and entirely realistic live sensation to Snarky Puppy’s excellent “We Like It Here” live album. The HD600’s famous mid-range sounded gloriously textured and front-and-centre during an enjoyable listen of Frank Zappa’s “Apostrophe”, with terrific stereo definition and space created between the hard-panned, double-tracked vocals. The bass definition wasn’t quite up there with a dedicated desktop amplifier, but I’d be more than happy to take this combination with me on my next holiday. 

    The Focal Clear’s somewhat metallic treble timbre benefited from throwing the SP2000T into “TUBE” mode, and with the volume wheel dialled-up to “55” I proceeded to work through Queens of the Stone Age’s “...Like Clockwork” album from go-to-whoa without touching a single button - it just sounded superb. 

    Final thoughts

    The A&ultima SP2000T might not be an inexpensive device in the scheme of portable audio solutions, but as a package it delivers the most exquisite user experience. From the moment you open the lid of the sumptuous wooden display box to the moment you hear the first bars of your favourite track, the SP2000T makes listening feel special. The SP2000T is a wonderful device to look at, to hold, and has a real timeless feel to its design - choosing a product like this is an investment into the way you want to experience music on an extremely personal level. And with the ability to extract stunning performance from IEMs and full-sized headphones alike, and then go and changing things up all over again by engaging the Triple Amp System, the SP2000T promises to give its lucky owner a comprehensive and continually surprising listening and ownership experience. 

    The Astell&Kern A&ultima SP2000T is the most comprehensive and impressive DAP I’ve encountered to date, and I’d certainly go out of my way to make room for it in my backpack or my desktop…or my life for that matter!

    Astell&kernDaps (digital audio players)Portable headphone amps and dacsTube audio