Astell & Kern Kann Ultra DAP Review

[amirm]

This is a review and detailed measurements of the Astell&Kern Kann Ultra DAP. It is on kind loan from a member and is on sale for US $1,499.

Forget any notion you have of a smartphone. This thing looks like one but is far, far heavier and thicker. Machining has left sharp corners which are unkind on fingers. The rotary volume control is slow and the display for it does not keep up.

On positive front it has wifi streaming including support for Roon! Didn't see that coming from a portable player. I tested both Roon streaming and playback using its USB-C cable. Yes I know, many will use an SD card with it but performance should be the same.

There are a set of balanced and unbalanced connections for Line and Headphone out:

As you see, labels are hard to read. The heavy weight of the unit comes in handy when using it on the desktop.

Astell&Kern Kann Ultra Measurements
Let's start with line out at max volume using balanced output:

This is impressively good for a DAP! Distortion is inaudible and noise floor is good. Both suffer though with unbalanced output:

Measuring noise by itself, it turns in very nice numbers, almost approaching dedicated desktop products:

There are selectable filters; I chose the fast linear which resulted in nice frequency response:

Linearity is as it should be:

Story becomes less good when we look at IMD distortion:

Jitter seems unsightly, though inaudible:

Multitone shows raised noise floor at lower frequencies:

That is a clue to issues there when we run distortion vs frequency:

To save my sanity, I only tested balanced headphone out, starting with 300 ohm load:

While we have plenty of power in max "Super" setting, there is much elevated noise. Even more strange is very limited power at 32 ohm:

We can see the strangeness in full exposition when we sweep impedances using high gain:

This is not how it should be for a device that is very focused on headphone output.

Conclusions
The Kann Ultra starts strong, turning in very good noise and distortion numbers as a DAC using balanced output. From there though, cracks in the foundation is seen, culminating in a headphone stage that is very poorly designed when it comes to gain management and low impedance loads. It should however be good if you use high impedance headphones.

Overall, this seems like partial improvement. And partial improvement is not what want to see in a device that costs $1,500.

I can't recommend the Astell & Kern Kann Ultra DAP.

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As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

 

[amirm]

Reserved for @RickS to kindly post the specs.

More specs are available here.

 

[JSmith]

Astell&Kern Kann Ultra DAP. It is on kind loan from a member

Thanks for the time in testing this Amir and to the member who sent it in.

Seems this is running dual ES9039MPRO's;

Another product where one needs to decode colours;

costs $1,500

Yeah, not competitive in this space at all.


JSmith

 

[respice finem]

Piggybank panther?

 

[antcollinet]

Why would anyone buy a device like this in preference to a mid range smartphone at half the price - even if they don't want smart phone functionality?

And given that almost everyone who wants a portable player will already have a smart phone, I really struggle to find a reason for this things existence.

Especially when you consider the UI performance.

 

[evanf]

In DAC mode: In an anechoic chamber with normal ears, this unit is transparent when playing music with 96db peak levels. 96db is very very loud. The effective noise floor of my room and hearing combined is 7db, so 89db is the threshold for SINAD audibility. Driver distortion is -80db WITH GOLD BERYLLIUM YAMAHA DRIVERS!!!!! And every other speaker is worse, -60db is the minimus of my Yamaha NS1000M speakers in large room far away (mostly .2-.15% THD).

As a headphone amp: burn it!

The phase intermodulation distortion needs to be considered with this unit to determine quality of imaging and soundstage

This site desperately needs relaxed, paper and pen noted long term listening preferably with friends helping out, prior to measurements in the reviews.

Also, there needs to be a music null tester with a level and phase matching ability, played into either a real speaker or an LCR speaker simulator. That is the only way to truly measure real music nonlinearities

 

[amirm]

This device is intended for headphone listening. Room doesn't factor in the equation. The headphone output clips severely causing massive audible problem for lower impedance headphones. So i suggest you park your justification elsewhere.

 

[antcollinet]

This site desperately needs relaxed, paper and pen noted long term listening preferably with friends helping out, prior to measurements in the reviews.

How would you propose to eliminate human perceptive biases from such a process? Seems impractical to me.

Also, there needs to be a music null tester with a level and phase matching ability, played into either a real speaker or an LCR speaker simulator. That is the only way to truly measure real music nonlinearities

You mean like deltawave? Whenever it is used (even though null testing no matter how well phase is matched will rarely give a perfect result) confirms the audibility assessments generated from the standard measurements performed here.

 

[Purité Audio]

Why would anyone buy a device like this in preference to a mid range smartphone at half the price - even if they don't want smart phone functionality?

And given that almost everyone who wants a portable player will already have a smart phone, I really struggle to find a reason for this things existence.

Especially when you consider the UI performance.

It’s a boy’s toy Ant that’s why.
Keith

 

[Old_School_Brad]

Hmm, is there really a market for such a device, considering most phones are already connected to services like Tidal and Spotify?

 

[HELIAS]

This is my device. Thanks to Amir for the review!

Bought it for the dual ES9039MPRO and the impressive power output on the spec sheet. DAC wise, as a device released in 2024, it does not seem to pull a considerable performance gap to the likes of Dual AK4499 Fiio M15 or AK4497EQ Lotoo Paw Gold Touch, released years earlier. The headphone amp part... Leaves me scratching my head. I can't say it doesn't meet the promise of the spec sheet, but there sure is an asterisk next to the numbers.

Besides, this JM20 dongle review just looks really funny in juxtaposition.

All things considered,

And given that almost everyone who wants a portable player will already have a smart phone, I really struggle to find a reason for this things existence.

I agree. My current solution - Qudelix T71 + whichever device I plug it into - offers enough power for every pair of headphones I have, including the demanding HE6se, and Qudelix sells a MagSafe case for it so it's not too hard to carry the T71 around. I would recommend this over a standalone DAP for anyone needing to use headphones with mobile devices.

 

[aravaioli]

I used to own the predecessor of this, Kann Alpha Max, and was shocked by how poor it was with low sensitivity, low impedence planar headphones. Horrible clipping with my Aeon 2, humiliated by any modest USB or BT dongles.
This device is designed to deliver volts only.

 

[Bland_username42069]

I have a different model but I use it as a remote to stream to different HiFi components and as a DAP. I’d prefer not to use Bluetooth headphones and I just don’t like using my phone for everything in my life. It allows me to leave the house without a phone.

They are far too pricey though

 

[Jimbob54]

Why would anyone buy a device like this in preference to a mid range smartphone at half the price - even if they don't want smart phone functionality?

And given that almost everyone who wants a portable player will already have a smart phone, I really struggle to find a reason for this things existence.

Especially when you consider the UI performance.

Leaving aside the actual device, Ive had the DAP vs smartphone discussion so many times on here. The usual points for a DAP seem to be "getting away from phone" , " dont need a dongle (a fair point)" and large storage (fair point but 128/256gb on phone storage is v common today) .

I'd be streaming anyway for the most part on either device and for me I'd get a sub £300 android device and a decent 2v dongle that has the power needed for most IEM/ Dynamic driver 'phones for sub £50 that would be slimmer , better UI etc and I would tether it to my main phone hotspot which is unlimited with maybe a few gb of downloaded for dead zones. Ive spent less than 1/3 price, possibly better performance (why anyone would be mobile in heavy hard to drive 'phones is beyond me ) and I have got a backup phone should my main phone again fall in the pot whilst in my back pocket.

 

[capslock]

They probably skimped on the power supply buffer or the reference voltage buffer for the DACs. LF signals cause significant droop on the rail or the reference et voilà, LF distortion.

I suspect the Wiim Pro Plus had the same problem initially.

 

[Jimbob54]

Hmm, is there really a market for such a device, considering most phones are already connected to services like Tidal and Spotify?

Pay a visit to headfi - there is your answer

 

[Kaiju]

Can you do iBasso daps? I am positive about them

 

[staticV3]

Can you do iBasso daps? I am positive about them

Send one in and Amir will do one. That's how ASR works.

 

[and072]

@amirm , is the output impedance on the single and balanced outputs normal?

 

[Turambar]

It looks strange indeed.

It's the first time, I think, that I see more output power delivered with a 300 ohm load, that with a 33 ohm load.

There are plenty of DAPs in the market, so I guess there are also quite a few people that are buying them. This one, apart from the strange thing with the output power, seems too expensive for what it's offering, in my view.