Can a tube amplified portable audio player make a difference in the audio quality you experience?

Astell&Kern A&ultima SP2000T Portable Digital Music Player

That’s what the A&ultima SP2000T player wants to prove and prove it they did in my extensive listening tests. This expensive player offers just about everything to the high-end listener, but it comes at a price.

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I laughed when I heard Astell&Kern were doing a portable player with tubes. What about the heat? How do you replace those tubes? Does it really sound better? The last question is the easiest to answer. It DOES sound better, plus it gives you the ability to tweak the sound because the tube circuit can be turned off, turned on, or mixed in a hybrid mode. The result is subtle, but there are audible differences in the sound that let you tune the A&ultima SP2000T to your personal taste.

Astell&Kern A&ultima SP2000T Portable Digital Music Player John Williams

Highlights

Astell&Kern A&ultima SP2000T Portable Digital Music Player

  • Beautiful, rock-solid construction.
  • Sweet-sounding DACS that add tube circuitry to the mix.
  • Multiple amplifiers, multiple DACS, multiple headphone outputs.
  • Wireless connectivity (Bluetooth and Wi-Fi).
  • Roon Ready. It can act as an endpoint in a Roon system and play everything in your library.
  • High-Definition Display.
  • Internal memory and support for a 1TB microSD card.
  • Can drive just about any headphone.
  • Includes a case and screen protector.
Introduction

I’ve listened to a lot of portable digital audio players, going way back to the original iPod. Over the years you could count on improved battery life, increases in the number of audio formats that can be played, and better sound quality. Every time I hear or purchase a new DAP I see and hear those improvements, and frankly, diminishing returns are setting in.

I had a lot of skepticism about this new Astell&Kern SP2000T digital audio player. It was well-appointed feature-wise and looked good. A&K has a storied reputation for building excellent products, and I’ve auditioned 3 of them over the years. The specs of this new A&ultima SP2000T player looked good, but perhaps the oddest feature is there is a tube in the audio output circuit. To some, the sound of tubes is the holy grail for high-end audio, somehow smoother, more refined, a nice throwback to the beginnings of Hi-Fi. But tubes in a portable player? It didn’t seem worthwhile or possible. How wrong I was.

A&ultima SP2000T SPECIFICATIONS

Features & Specs

Body Material & Color:

Onyx Black Aluminum

5″ 1280×1080 FHD Touch Display
Octa-Core CPU
USB Type C for Charging and PC (Windows 7,8,10)/MAC (MAC OS X 10.7 and up) interface
Dimensions of 3.07″[W] x 5.55″[L] x .68” (17.5mm) [H]
Supports WAV, FLAC, WMA, MP3, OGG, APE, AAC, ALAC, AIFF, DFF, DSF, MQA
Supports up to 384kHZ 32-bit PCM and DSD512(1bit 22.4Mhz) Stereo
Includes Unbalanced 3.5mm Out and 3.5mm Optical Digital Output, Balanced Out (supports 2.5mm 4pole / 4.4mm 5pole)
Windows 10 (32/64bit)
MAC OS X 10.7+
Wi-Fi, Bluetooth v5.0
Weighs only 10.89 ounces
256GB [NAND] internal storage with microSD card slot supports up to 1TB
4,200mAh Battery with up to 9hours playback time

Audio Performance
 

ESS ES9068AS x4 (Quad-DAC)
Frequency Response (Condition 20Hz~20kHz):

+/- 0.024dB Unbalanced, +/- 0.038 Balanced

Single to Noise Ratio @1kHz:

121dB Unbalanced / 123dB Balanced

Crosstalk @1kHz:

-137dB Unbalanced / -142 Balanced

THD+N @1kHz:

0.0003% Balanced or Unbalanced

Output Impedance:

1.5ohm 3.5mm Unbalanced / 1.0ohm 2.5mm Balanced

Clock Jitter:

25ps (typical)

Reference Clock Jitter:

70ps

KORG Nutube 6P1 Vacuum Tube
Output Level (Condition No Load):

3.0Vrms unbalanced / 6.0Vrms Balanced

List Price:

$2499.00

Weight:

10.89oz

Website:

Company Site

Company:

Astell&Kern

SECRETS Tags:

Digital audio player, Astell&Kern, DAP, Roon, Spotify, Tidal, Qobuz, MQA high-resolution audio, Audio Player Review 2022

Plugins

Design

Where to begin?

Opening the box reveals well-thought-out packaging. You’ll see the DAP packed in a real wooden box.

Wooden Box

Inside is the SP2000T player, a user guide, a leather case, and a USB cable. There’s also a screen protector. It’s all very thoughtful, and it will let a buyer know they made a good choice.

Guide

I don’t think there is a more fully-featured DAP in existence. Physically, this player is beautiful in black, gray, and gold highlights. It’s angular and has a lovely high-resolution display on the front, with a unique back display that can tell you which combination of output amps you are using, or at the choice of the user, a color code can tell you what format of audio is playing. The format also appears on the front screen along with the album art.

Light

This is a very solidly-built high-end device, a little smaller than my iPhone 13 Pro Max, and similar in weight. There are many small details in the build quality designed to keep the audio at the highest quality, including a structure that uses magnetic forces to float the amp in the air, thus minimizing noise from the vacuum tube itself, which is generated when it is exposed to mechanical impact or vibration. Astell & Ken also apply shields so that noise and electromagnetic interference, which occur when the countless parts are in operation, do not affect the audio circuitry.

The SP2000T has taken it a step further by applying highly conductive, hyper-pure silver plating on the existing shields providing excellent audio performance.

As a first in my experience, the ST2000T used 4 ES9068AS DACs, this allows two DACs per channel for dedicated decoding. Astell&Kern claims the SP2000T achieves a more detailed and balanced sound with great depth and spatial realism.

About that tube

With the SP2000T, you can select between TUBE AMP mode, OP AMP mode, or the brand-new HYBRID AMP mode.

OP AMP mode delivers extreme clarity and dynamic sound, while TUBE AMP mode provides a uniquely warm and musical sound.

HYBRID AMP mode – a first for digital audio players – enhances the resolution and clarity of the existing TUBE AMP mode to express more musical detail. HYBRID AMP mode combines the advantages of retro analog performance and high-resolution output, giving you the pleasure of a brand-new tonal characteristic.

The tube itself is a portable-friendly dual-triode KORG Nutube, for a unique tube sound. Nutube offers a reliable continuous playback time of approximately 30,000 hours. It features an anode grid filament structure that operates the same as a triode vacuum tube. It’s much smaller, consumes far less power, and yet delivers the same audio with rich overtones according to Astell&Kern. We’ll put those claims to the test in the listening experience detailed below.

To get started with the SP2000T you’ll need to charge it. My review sample which was factory fresh had an 88% charge out of the box, but I charged it to 100% with the supplied USB A to USB C cable using a USB hub. A full charge looks to take around 3 hours. I averaged about 9 hours of use before it needed to be charged again.

There’s a small microSD slot, which has a dust protector on it. I removed that and placed a microSD card filled with music that I used in my FiiO M15 DAP, which is my reference player. It contains a mix of MQA, various resolution FLAC files, some DSD tracks, Apple ALAC, and even some lowly MP3 tracks. Speaking of storage, the SP2000T comes with 256 GB of internal storage and allows you to add a microSD card with up to another 1 TB of storage. The SP2000T does get warm with use, but never hot. It was no warmer than my FiiO M15 which is completely solid-state.

You’re not stuck with playing music off a microSD card. The SP2000T gives you Spotify, Tidal, or Qobuz if you are subscribed, and supports MQA playback.

I tried a variety of headphones but did most of my listening with Focal Clear Mg headphones, which are neutral and extend deeply into the low end while having good imaging and a smooth high end. I also along the way sampled headphones I have on hand from Sennheiser and AKG.

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In Use

In my tests, I tried a variety of tracks, from classical to hard rock to new age to acoustic jazz. It’s difficult to generalize about the sound, because of the multiple listening modes on the SP2000T. Still, let me give you a high-altitude overview, and then I’ll get down to specifics.

Closeup

Overall, I liked the tube and hybrid settings the best. I listen mostly to acoustic music, classical, and jazz. In the tube mode, the highs were quite smooth, while the soundstage on many tacks seemed to slightly lessen in width. I didn’t find this a negative, as soundstage is always exaggerated on headphones anyway. In general, I found that the more ‘live’ the acoustic space, the more the width or soundstage was narrowed.

One issue the SP2000T seemed to solve, which was a worry, is microphonic distortion. I mentioned this earlier in my review. If you are familiar with tube gear, just touching a tube will generate a vibration that you will hear as an unpleasant audio signal. I wondered if that would be a problem in a tightly packed device. Turns out, it isn’t. Astell&Kern have come up with a floating magnetic structure for the tube mount, and in my tests, sound emerges from a silent background, even when I tap the case.

Listening in a pure solid-state mode, I found the results hyper-realistic. Again, with rock or some new age, this was not a disadvantage. For example, in the track ‘Disc Wars’ from the Tron: Legacy album, I preferred the solid-state amp sound.

The SP2000T gives you a lot of ways to tweak the sound of any track. Some users will find that a daunting and wasteful task. Others, especially many audiophiles, will enjoy the experience and get their music closer to the sound they want.

On to some specifics:

Sibelius: Complete Symphonies

Sibelius: Complete Symphonies – Paavo Berglund conducts the Bournemouth Symphony in a complete cycle of all the Sibelius Symphonies. These are very realistic recordings, and the project stretched over many years. I found the SP2000T sounded best in either the tube or hybrid setting. The image of the orchestra seemed realistic, and the high frequencies were smooth and not overemphasized. There’s not a lot of low-end in these works but it was there when called for. Like most of my auditioning, I listened through the Focal Clear Mg headphones. The files were 16/44 FLACs.

An Oxford Christmas

Ralph Vaughan Williams: An Oxford Christmas – This is a 24/96 high-resolution album, and it was a good test of the audio chain. Again, I liked the tube or hybrid mode the best. Voices were firmly locked into position, even though the recording venue was a large acoustic space. The solid-state amp sounded good too, but for my taste a bit too sharp. It was great to have choices.

Dune: Original Soundtrack

Dune: Original Soundtrack – A very electronic soundtrack, which I thought sounded better playing without the tube in the circuit. I used the Op Amp mode. It had a wide soundstage, deep bass, and sparkling high frequencies. Dune sounded noticeably better on the SP2000T than on my FiiO M15. This is an MQA album that I played through Tidal rendered at 24/48.

Tron Legacy

Tron Legacy: I listened to Disc Wars on the SP2000T, a great test track for any high-end system. This 16/44 CD rip was breathtaking. I’d give a very slight edge to the tubeless solid-state sound, but in hybrid mode, the sound was great too.

Deep Field

Deep Field: Eric Whitacre – Symphony with Chorus. A very interesting musical impression of images from the Hubble Space Telescope. A 16/44 FLAC, that sounded better in the hybrid or tube mode. The imaging was solid, and I find this CD a great listening experience.

In general, the better the source material, the better the SP2000T sounds. It is devastatingly revealing of compression, grain, distortion, and noise. In that way, this DAP is like any high-end source component. Feed it the best source material you have. Headphones are already very revealing, but with the SP2000T playing the source, you’re going to hear any shortcomings in your music.

Conclusions

Now comes the hard part. At $2499.00 the SP2000T is not an impulse buy, but that’s true of any high-end component.

Likes
  • Packaging, design, and presentation are first-rate.
  • Setup is easy and fast.
  • The HD screen is bright and color accurate.
  • The internal amp(s) can drive any headphones.
  • The sound is sublime listening to the solid-state amps, and for many audio files, it’s improved with the option of the tube amp or the hybrid mode.
  • Roon compatibility is a real plus.
  • The GUI is easy to operate, and well designed.
Would Like To See
  • A more complete getting started manual. The quick start card is silver ink on black paper. It’s hard for my tired eyes to read. You can download a manual from Astell&Kern, which is very complete and easy to read.

It would be a waste of money to buy this to listen to MP3s and low-quality CD rips. However, if your collection contains a lot of high-resolution files, and/or DSD sourced material, you won’t be disappointed. It will render your music at the highest possible quality, and let you select from multiple amplifier topologies to match your personal listening taste.

Audio-wise, I’ve heard nothing better from a portable player. This DAP has a vast number of features, and the ability to add a tube to the circuit is not a gimmick. It changes the character of the sound. For a person who appreciates a well-engineered tube component, this design is a real plus. The fact that they were able to add a tube and have it last for many thousands of hours and defeat microphonic noise is a huge plus.

While this DAP supports Bluetooth, I was very happy to see it work as a Roon endpoint over Wi-Fi. I think the audio quality is better than Bluetooth and I love having all my music available on this DAP anywhere in the house.

For many audiophiles, the SP2000T is going to be priced out of their budget. Still, it’s rare to review something that is so feature-complete and not disappointing in some way. Astell&Kern have put a lot of thought into this product. In many ways, I think it is a better and more portable solution to home music listening than being tied to a high-quality headphone amp. For travel, it can’t be topped.

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