The product (both SR25 and SR15) was loaned to me for the review purpose in exchange for my honest opinion. The review was originally posted on my review site, and now I would like to share it with my readers on Head-fi.
Manufacturer website: Astell & Kern, Available for sale directly or from on-line retailers like Audio46
Intro.
When audiophiles hear the name Astell & Kern, the word “budget” or “entry level” is not the first thing that comes to their mind. But with an exception of two bonus models, KANN (extra power) and SA700 (homage to the classic), the latest line up of A&K portable players is actually partitioned into A&norma (entry level), A&futura (mid-fi level), and A&ultima (summit-fi level). Relative to A&ultima flagships, A&norma is a budget model where the original SR15 design was noticeably scaled down. But, would the same hold true with a new SR25?
While being familiar with SP1000, SP1000M, and SP2000 A&ultima flagships which I have reviewed before, their A&norma SR series was never on my radar until A&K asked me if I’m interested to hear their upcoming SR25. I wasn’t familiar with the original SR15 either, but was well aware of its tilted screen which IMHO stood out as being outside of “norma”. Being intrigued by the design and curious about the sound, I agreed to take a listen, and later extended my curiosity to how it compares to SR15. Now, I’m ready to share what I found.
Unboxing and Accessories.
I received SR25 without a packaging box, so there is nothing much to write about the unboxing or accessories. But I have already seen SR25 on-line unboxing, and it looks like a compact basic packaging with a manual, a few sets of screen protectors, and a premium quality charging/data usb-c cable.
No case was included, it’s optional. Makes sense since this is their entry level model which needs to be distinguished from upper level flagships.
Design.
You can’t start talking about the design of SR25 without mentioning the tilted screen. A&K created quite a stir when they introduced the original SR15. The idea behind it was based on the analysis of how we hold the DAP in our hand, especially as small and compact as SR15. It is different when it comes to balancing a bigger and heavier DAP, but A&K design team decided that a tilted screen will be aligned “straight” when we naturally tilt our wrist holding SR15. SR15 display does look straight in my hand, and it was less noticeable when looking at the DAP due to a darker color of SR15 body. With a silver color of SR25, the tilted angle of the black screen is a lot more noticeable, though it still works similar to SR15 – relative to the angle of my wrist the display was aligned straight.
From the exterior perspective, the design went through a lot of changes between SR15 and SR25. The chassis are wider and longer, now measuring 63.5mm x 16.1mm x 108.3mm to accommodate a bigger upgraded HD touchscreen, from 3.3” (SR15) to 3.6” (SR25). The display is not just bigger, but also has a higher resolution and deeper and more vibrant colors. The difference here is really night’n’day going from original 480x800 display to higher resolution 720x1280 WVGA TFT LCD touchscreen. And with a bigger screen and slightly bigger size, the weight went up as well, 178g (SR25) from 160g (SR15).
The body is still metal (aluminum) with an asymmetric tilted screen in the middle. The color of SR25 is moon silver, and like the original SR15, the back has carbon fiber glass inlay. The bottom of the chassis has usb-c port for charging and data, and next to it is a spring-loaded microSD slot for a flash card, so you can expand its 64GB internal memory with up to 1TB of external. Right side at the top has the volume wheel, taller/deeper than original SR15, and with a new watch-crown design. The top has 3.5mm SE headphone output, 2.5mm BAL headphone output, and a power button with a typical long press to turn power on/off and short press to turn screen on/off functionality. On the left you will find 3 identical playback control buttons with play in the middle and skip above/below it. The shape of the buttons is now similar to their upper end models.
The overall design of SR25 has a more premium look to align it better with futura and ultima series, including all these angled asymmetric lines on the front, back, and all around. SR25 really does look like mini-me version of their upper end models.
Under the hood.
While a few things haven’t changed moving from SR15 to SR25, like dual CS43198, or 64GB internal storage, or the headphone output voltage with 3.5mm SE (2.0Vrms) and 2.5mm BAL (4.0Vrms), a lot of others things have been updated. Still get playback of all the popular formats of WAV, FLAC, WMA, MP3, OGG, APE, AAC, ALAC, AIFF, DFF, DSF, MQA, with sampling rates of PCM (8kHz-384kHz), DSD64 (2.8MHz), DSD128 (5.6MHz), plus SR25 now also adds native support of DSD256 (11.2MHz).
As already mentioned, low res 3.3” 480x800 screen has been upgraded to 3.6” 720x1280. No more micro-usb port, SR25 now up to date with USB Type-C. Bluetooth also saw a big update with SR25 now supporting LDAC codec in addition to aptX HD. Still OpenApp and MQA support, and SR25 fw is based on Android 9.0 with additional sound optimization, including Performance Mode to optimize playback of high res audio files.
And despite using the same size battery (3,150mAh 3.7V Li-Po), A&K managed to double the playback of SR25 in comparison to SR15. As a matter of fact, while playing 24b/48k high res FLAC, 2.5mm balanced output, using average sensitivity/impedance IEMs at normal listening volume level of v50 and with wifi/BT off, I was getting a solid 22hrs 25min of playback time!
GUI and Open APP Service.
Consistent with my review format, I always like to cover GUI details. But considering it is the same interface as their flagship SP2000, please refer to my Head-fi review of SP2k or the full review of SR25 on my site. There is no need to copy’n’paste again that detailed coverage of GUI and open App Service details. Though, one thing I do want to mention – the PEQ adjustment in SR25 has a more noticeable effect on the sound. I can only speak for SPK and SP2k where PEQ still had a subtle effect, and I was very pleasantly surprised that in SR25 the parametric equalizer actually more usable!!!
Sound Analysis.
The sound analysis of SR25 was done using 64 Audio U18t, playing a selection of the test tracks, such as Agnes Obel “The curse”, Sandro Cavazza “So much better” (Avicii remix), C-Bool “Never go away”, Ed Sheeran “Shape of you”, Counting Crows “Big yellow taxi”, Galantis “Hunter”, Alan Walker “Darkside”, Iggy Azalea “Black widow”, Indila “Boite en argent”, Robin Schultz “Oh child”, David Elias “Vision of her”, and Michael Jackson “Dirty Diana”.
Similar to its predecessor, I found SR25 to have a neutral balanced signature with a more natural fuller body tonality, not only with U18t but other iems and headphones.
Overall, the sound has good dynamics (vertical expansion of peaks), never felt compressed or congested. And I found SR25 to have a black hiss-free background even with some of the most sensitive IEMs, like Andromeda and Solaris.
The soundstage expansion is very spacious, wide, and with a good imaging resulting in a relatively accurate placement of instruments and vocals. That is how it sounds from 2.5mm (BAL) output. But when switching to 3.5mm (SE), the soundstage width shrinks. Here are more differences between BAL and SE outputs as I hear it.
2.5mm vs 3.5mm
The difference in power output is definitely noticeable since while going from BAL to SE I had to raise the volume by 10 clicks to match it. Another very noticeable difference is BAL output having a wider soundstage and blacker background. Other than that, the sound signature and tonality are nearly the same.
Comparison.
In every comparison I used 64 Audio U18t IEMs, volume matched while listening to the same test track between DAPs.
SR25 vs SR15 - the tonality of these DAPs is nearly the same, both having a neutral balanced signature with a more natural fuller body tonality. And that is where all similarities end because SR25 technically is by far superior in comparison to SR15. SR25 soundstage is a little bit wider and has more depth, resulting in a better imaging and a more accurate positioning of instruments and vocals in space. Also, the sound of SR25 is more layered, more separated, and with better vertical dynamics expansion, making SR15 sound flatter and more compressed in comparison. This technical performance difference is what sets SR25 apart from SR15 entry level performance, elevating SR25 to a more solid mid-fi level.
SR25 vs SP1000 SS – believe it or not, the tonality here is not too far off. I do hear SPK to have a wider soundstage, stretching further left/right, and SPK also has more sparkle in treble and a little more transparency in upper mids. But overall tonality has a lot of similarities, being more neutral with a more natural body and great retrieval of details. SPK has better technical abilities with more air between the layers of the sound, as expected from a flagship model.
SR25 vs Plenue R2 - a lot of similarities in this comparison, though some subtle differences as well. With soundstage, SR25 stretches a little bit wider, not by a whole lot, but noticeable. Tonality is very similar as well, neutral, detailed, with a natural body. But, R2 has a little more low end impact and a deeper sub-bass rumble. From a technical perspective, especially with high res FLAC files, SR25 sound is more layered and with a little better vertical dynamics expansion. Definitely not night'n'day difference. I think in this comparison, those who enjoy sound tweaking and only care about local audio playback might consider R2. But if you want access to streaming and more advanced Bluetooth with hi-res codec support, and better battery life, SR25 is the way to go.
SR25 vs Hiby R5 - more similarities in tonality between these two, but when it comes to technical performance, the gap is wider. R5 doesn't have a wide soundstage to begin with, and it is noticeable in this comparison with SR25 expanding its staging wider. Tonality is similar, being neutral and more natural. But the layering of the sound and vertical dynamics expansion is quite different with SR25 having more air between layers and more dynamic peaks, while R5 sounding more compressed and flatter in comparison. Both support hi-res Bluetooth codecs and have access to streaming apps, though with SR25 you have to side load it, while with R5 you just download it directly from Google play store.
SR25 vs iBasso DX160 - while in previous comparison there was more similarities in tonality and more differences in technical performance, here it is actually the opposite. Both have a wide soundstage expansion, and actually DX160 sounds wider and more holographic. They also have a very layered and dynamic sound. You can hear how well instruments are layered and separated listening to both daps, and their vertical dynamics expansions is impressive. But with a tonality, SR25 goes for a more natural fuller body sound, especially in mids, while DX160 has a more revealing and more transparent mids/vocals, making its tonality brighter. It's really up to a personal preference, or perhaps the pair up synergy with IEMs and their corresponding signature. Both allow to side load apps, though DX160 doesn't have any black list limitations. Both have a similar BT performance, which is not as strong when it comes to coverage distance.
SR25 vs theBit Opus#1s - I thought some might find this comparison interesting as well due to the same DAC chipset. There are quite a few differences here. Starting with soundstage expansion, it's probably one of the few things where they are similar, in both width and depth. Also, both have a dynamic and layered sound. But the tonality has a noticeable variation, with SR25 being more neutral and more natural, with a fuller body more organic mids/vocals, while Opus#1 has a thinner and brighter mids/vocals and splashier treble response. That made Opus#1 tonality less natural in comparison. And of course, Opus#1 is playback audio only device, not even a Bluetooth support while SR25 adds BT and wifi support to side-load apps for streaming.
SR25 vs FiiO M11 Pro - Pro version of M11 definitely improved the performance of the original M11, making it more suitable for this comparison. Both have a wide soundstage expansion, actually very similar in width and depth. Technically, they also have similarities in layering and separation of the sound and vertical dynamics expansion, something I wouldn't be able to say about M11 but can report as Pro improvement which now can match SR25. But tonality is different, and it is noticeable. SR25 has more sub-bass rumble which goes deeper. Also, SR25 upper mids/vocals and treble are more natural, smoother, while M11 Pro is brighter when it comes to vocals and also a little splashier in comparison with lower mids. This is a difference where you will have to decide which one pairs up better with a signature of your preferred IEMs or headphones. Both can side load streaming apps and support various high res BT codecs, though SR25 BT performance is a little weaker.
SR25 vs SR15:
Pair up.
Here is how SR25 pairs up with various IEMs, earbuds, headphones. For the reference, I indicated the volume level in (v). Each one was tested with a balanced cable.
Empire Ears Legend X (v70) - wide soundstage expansion, not super wide, but decent. The typical L-shaped sig of LX in this pair up becomes more V-shaped. Mids are there, clear detailed natural, but bass is ear-shattering with a very powerful deep sub-bass rumble and strong rounded mid-bass punch. The bass is complemented by sparkly clear treble. Perhaps, the signature is more reversed J-shaped. And that bass slams very hard, making LX woofers to rattle your brain.
VE Sun Dice (v92) - wasn't sure how SR25 will be able to handling these 180ohm earbuds. The sound is still open and nicely expanded since earbuds are sitting on top of my ears. But the sound sig is a little different, not as balanced like in some other pair ups, but rather more mid-forward. Bass is slightly attenuated here, not rolled off, but just attenuated. Mids/vocals are clear, organic, soulful, smooth. Treble has a nice well controlled sparkle as well. Personally, I preferred Sun Dice pair up with sources where its signature is more balance, but if you want to focus more on vocals, this will be pretty good.
Campfire Audio Solaris OG (v43) - nicely expanded wide soundstage, with a little more out of your head expansion, giving it more depth than width. Overall sound sig is balanced with a smoother tonality. Bass has a nice analog flavor with a deep rumble and an average speed punch (attack is a little slower, typical for DD performance). Mids are smooth, natural, detailed, not too revealing. Treble is well controlled, not exaggerated or fatigue.
Campfire Audio Andromeda (v45) - there are a lot of similarities in this pair up with Solaris. The soundstage has a similar width and depth, with more out of your head depth. The signature is also balanced and the tonality is smooth, but a little more revealing. Bass has a good rumble and decent punch, but the quantity feels closer to neutral here, definitely not as elevated as Solaris. Mids/vocals are smooth, natural, and at the same time with a better retrieval of details than Solaris. The same with treble, I hear more sparkle with Andro than Solaris.
64 Audio Trio (v66) - wide soundstage expansion, actually soundstage is a little more holographic in this pair up. The signature is nicely balanced with a natural detailed tonality. Bass is very powerful in this pair up, going deep with a textured rumble and faster mid-bass punch. Mids are natural, detailed, with an excellent clarity, but the presentation is pushed slightly out of your head. Treble has nice sparkle, non-fatigue, and still with a good sense of airiness.
64 Audio U12t (v66) - I hear a wide soundstage expansion, with a little more out of your head depth. The overall signature is balanced, with a slightly mid-forward presentation. Bass has a good depth and mid-bass punch, but it's closer to neutral in quantity. Mids/vocals are clear, natural, detailed, with a little more forward presentation in comparison to Trio. Treble is non-fatigue, well controlled, clear, and with less sparkle than Trio. Actually, with SR25, Trio sounds more fun, while U12t is more laidback.
Beyerdynamic T5p 2nd (v79) - wide soundstage with more depth than width. Nicely balanced signature with a clear detailed tonality. Deep analog bass extension with a textured rumble and fast mid-bass punch. A little thinner neutral-bright mids/vocals with a nice layering and separation of sounds. Good treble extension with a nice well controlled sparkle and airiness. Surprisingly good pair up, especially impressive bass extension.
Meze Audio Empyrean (v91) - wide soundstage expansion with a little more depth than width. The overall sig is balanced and tonality is smooth, but the sound presentation is more laidback. This pair up is not exactly what I’m used to hear with Empyrean, bass doesn't extend as deep or punches as hard, and mids are a bit too smooth and laid back. Treble is very good, detailed and sparkly. SR25 has no problem driving these planar magnetic headphones loud enough, but not to their full potential.
The bottom line, can it drive earphones and headphones loud enough? Without a doubt it can! I was even able to drive my open back 470ohm impedance ATH-R70x at 124 (out of 150) volume. But, with more demanding higher impedance headphones and some planar magnetics that need more current, I don’t think SR25 was able to push them to their full potential.
Wired and wireless connections.
Besides being a portable DAP, you can expand SR25 functionality as a transport to drive external DAC/amp, to use external AMP, or to turn the DAP into usb DAC. And of course, you don’t have to be limited to wired headphones, and can take advantage of Wireless Bluetooth connection.
Wireless/Bluetooth.
Tested Bluetooth Wireless with various headphones, SR25 paired up within seconds and had the acknowledgement message on the screen that it was connected using corresponding codec. I was able to change volume from SR25 and from wireless headphones, as well as control the playback and skip tracks remotely. Wireless connection worked about 20ft away from SR25 in open area. This is not the strongest performance like in SPK or SP2k, most likely due to reduced power of BT transmitter to save battery life in SR25.
Line Out.
Connected to FiiO E12A, I had to select Line Out from notification bar and was able to control the volume from both external amp and SR25. If you need to color your sound with an external amplifier or need to drive more demanding headphones, access to LO is convenient.
USB Audio Out.
Connected to Lotoo S1 USB DAC/amp using Lotoo’s provided cable. In notification bar of SR25 have to be sure External USB is selected to enable USB Audio mode. Volume was fixed on SR25 at 150, and I can adjust it from S1. Very clean and transparent sound based on sound characteristics of S1 DAC/amp while using SR25 as a digital transport.
USB DAC.
Recognized right away by my ThinkPad T480s (Win10Pro). In notification bar of SR25 have to tap USB Mode to select DAC. Volume can be adjusted from Laptop or SR25. No need to install any additional drivers, and the sound was typical of SR25 headphone output.
Conclusion.
Every time I get a chance to review A&K DAPs, I get reminded how loyal their fanbase is. Often after receiving different DAPs for review purpose and mentioning about it on FB or in corresponding Head-fi thread, people ask me about comparison to other DAPs in the same class, including if the price difference is justified. When I acknowledged about receiving SR25 for review, most of the questions I received were from existing SR15 owners, asking for comparison and if it makes sense to upgrade. That was exactly the reason why I asked A&K for SR15 loaner in addition to SR25, to answer the burning question about side-by-side comparison.
Similar to SP1000 vs SP2000, price of SR25 remained the same as SR15. But SP2k upgrade was more about the finetuning, while SR25 upgrade was a step forward. SR15 and 25 share a similar sound sig, and that’s about it. As it was mentioned in the review, technical sound performance of SR25 is superior to SR15. And on top of that, you have a bigger higher resolution display that looks night’n’day in comparison to SR15, usb type-c (vs micro usb), addition of LDAC (not holding my breath for 4.4mm, but LDAC broke the ice), stepping up to DSD256 (vs DSD128), PMEQ with a more noticeable sound adjustment, and the battery which now lasts almost 22.5hrs (vs 10hrs). For the same price as SR15, it is no-brainer!
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