Astell & Kern SP4000T Review: A DAP For All Listeners

Astell & Kern's DAP lineup is nothing short of impressive. From introductory models like the SR35 to flagships like the SP4000, Astell & Kern finds a way to make it into an audiophile's setup. Their latest release is a variation on their new flagship, and we had the pleasure of listening to it here at Audio46. The SP4000T is a digital audio player that combines high-end portability with the analog technology of tubes, creating a unique combination ideal for high-end setups. Is the SP4000T the DAP you should upgrade to? Or is the original SP4000 still the ultimate flagship? This review will analyze all the details and give you the rundown on all you should know. 

If you've held an Astell & Kern DAP before, the SP4000T will feel familiar to you. The A&K DAPs have always been made exceptionally well, bearing a bit of weight to make the device fairly heavy in your hand. The stainless steel and copper body is shiny and has a glossy finish, making the entire device look and feel luxurious. While you could let the stainless steel speak for itself, it is prone to fingerprints, so the included leather case becomes a nice and much-needed accessory if you want to keep your device safe and in good condition. 

A great design choice that was made with the SP4000T is the window in the back of the device for the tube to be displayed. While you can't really see it when the SP4000T is turned off, you can definitely see it lit up in red when the player is on and in use. A great addition on top of that is the case also having a little cutout that allows you to see the tube, allowing you to have the protection on the DAP as well as an aesthetically pleasing feature. 

Astell & Kern user interfaces are very simple and easy to use. It is the same interface that you see on models like the SP3000T, SP3000, and SP4000, and even the physical buttons are the same. Having the tactile controls is a nice way to easily navigate through your listening without having to turn on the screen every couple of seconds. The dial on the side is smooth and adjusts volume very precisely. The buttons on the side allow you to skip, replay, or pause the track you're on. The SP4000T's dial button also serves as a power button, which is helpful when you need to manually reset the device or quickly shut it off. While they may not be labeled, it is straightforward to figure out the controls without needing to refer to a manual every time you want to do something. 

In terms of the user interface, Astell & Kern makes a very easily manageable setup for you to customize as you go, which you see on the SP4000T. You have a lot of options for how you can listen to music on the device, and some of that involves downloading apps to log into your favorite streaming services. Spotify, Tidal, Apple Music, Qobuz, and many more are available for you to download so you can have access to your favorite way to listen. The SP4000T has an interface that is fast and smooth to use, and I found that extended use didn't make it lag or run slower as the battery declined. The performance speed and fluidity of the screen and controls were impressive on the SP4000T, and it made using it no trouble at all in any environment.  

Some DAPs aren't equipped with enough power to drive all the headphones you have in your collection. Astell & Kern ensures their units have a high power output to drive some of the most demanding headphones. I was very impressed with the power output of this device, as it was able to drive some demanding headphones, such as the Sennheiser HD 660S2 and the Abyss Diana MRx. The SP4000T was able to reach high volumes and not get distorted or start clipping to reveal sonic artifacts. 

Though the SP4000T is a very powerful source, you still have the option to pair it with in-ear monitors with no issue. The power coming out of the player is very strong and can be made even stronger with the high-driving mode, where you get an increase in gain to get to louder volumes faster. This is a feature first seen on the SP4000, and it carries over to the SP4000T to make sure both devices can deliver a premium performance for all headphones. 

Essentially, the main feature of the SP4000T is to have all your music allocated to one device. Be it streaming, SD card, or locally downloaded files, the SP4000T can hold all your music and then some with 256GB of built-in memory. You can also insert up to 1.5T on an external memory card for even more space. But besides playing your music, what else can you do on the SP4000T?

One highlight that gives the SP4000T its name is the tube amplifier. The Triple Tube Mode is a feature that makes its debut on the SP4000T. Like the SP3000T, you have the option for current adjustment, and you have complete control of how analog or digital you want your sound to be. The three tubes have different functions and specifications that allow you to cater to your personal sound preferences. Based on how you can adjust the current flow and operation of the tubes with your sound, there are 54 possible combinations that you can choose from to enjoy your listening. Additionally, you have the option to activate the tube amps or use the solid-state amplifier, and an additional third option to use a hybrid between the two. You'll know if the tubes are activated based on the light that appears on the back of the SP4000T that shines through a window into the device's tubes. 

The SP4000T offers a lot of other options for sound customization. You can open up the built-in EQ and adjust the tuning to be exactly how you like. There are 7 DAC filters to choose from, and depending on the headphones or IEMs you use, you may find you like some over others. With wired and wireless connectivity options, you are set to use this DAP as a source or an additional amplifier for your listening setup.