The segment of portable amplifiers is a specific, currently rather unsystematic niche in the portable audio market. Most portable sound connoisseurs prefer solutions that are as simple as possible in terms of functionality, convenience and portability. The classic connection – the player and in-ear headphones works perfectly for most. However, there are a number of times when purchasing a portable amplifier is a great idea, or even a necessary step.
Why is this niche specific? Because there are currently no system requirements for devices in this segment. The demand and demand for high-end portable amplifiers is now on the rise, the mass market for high-end portable amplifiers is just emerging.
It all started with numerous devices – DAC amplifiers, which in terms of sound quality at one time were ahead of most players (the mass market of which was also in its nascent stage) and actually had advantages in interaction with the user due to the use of a smartphone as a source, while players were just getting on their feet and had numerous problematic issues related to the operation of operating systems, the use of very old touch screens of poor quality and other numerous UX/UI problems. In addition, the amplifiers offered unique (by today’s fairly uniform standards of portable audio) engineering and, most importantly, sound. Due to this, some models built on FPGA matrices and tube amplification have acquired the status of legendary devices.
Over time, DAC amplifiers began to expand their functionality – to work with wireless technologies to receive a digital signal, to work separately in DAC mode, in amplifier mode (and even in preamplifier mode for special enthusiasts). Then we saw the first devices that were actually portable amplifiers, but it was still too early to talk about the outstanding quality of their work, as well as the feasibility of their use.
Meanwhile, Hi-Fi players have started to make a serious boost in both sound quality and usage scenarios and now boast the use of Qualcomm processors, Android 11 operating system, beautiful touchscreens and access to streaming services, which has given them a significant advantage in the eyes of users.
To date, DAC amplifiers are considered mainly as solutions that dump prices relative to a player with a similar sound level due to the exclusion of the components listed above, which increase the cost of players. Or as a mobile desktop solution that can be used in portable scenarios.
Thus, the rapid development of portable audio in recent years has led us to excellent sound quality in players not only of the higher, but also (often) of the middle price segment. And now connoisseurs of portable audio players face questions of a completely different nature. Operation of devices no longer causes reactions of irritation, sound quality for affordable money no longer arouses thoughts about compromising sound. Manufacturers are even to a certain extent able to cope with quite serious amplification characteristics in relation to the size of the player (mostly in their flagship and experimental models). But this is still not always enough.
Even with high-quality DACs on board, players are still not able to satisfy all the needs of consumers regarding amplification. After all, having an excellent player, users want to fully reveal the potential of their headphones, regardless of whether they are in-channel headphones, which at first glance are not too demanding, but will always respond positively to high-quality amplification (such as Fir Xenon 6 , JVC HA-FW10000 and a number of other high-level dynamic in-channel headphones), or such IEMs, which without a serious reserve of power can not even be approached (models from some manufacturers using a 12mm isodynamic radiator from Tin HiFi ), or if the user wants to enjoy the quality sound of full-sized headphones with opening to their full potential (this is, of course, the strongest argument in favor of a portable amplifier).
Naturally, the portable audio industry began to gradually give us amplifiers worthy of pairing with top players to reveal the full potential of the devices. Perhaps the creations of Mass Kobo, Phatlab, Romi Audio, Bakoon and Aroma Audio are not widely known, but are highly (!) respected by experienced audiophiles for the quality of amplification and the amount of new emotions they can bring to their owner.
The recent releases of serious portable amplification solutions from Romi Audio and Brise Audio (by the way, the first audio device from a premium cable manufacturer) only confirm the development of demand for this segment, which will continue to grow.
Meanwhile, understanding the development trends of the industry, the smart and talented guys from Astell&Kern also decided to confidently but cautiously enter the segment of portable amplifiers and presented their first (and I’m sure not the last) portable amplifier Astell&Kern PA10.
Kit, design and technical characteristics
The kit consists of an amplifier, a USB Type-C charging cable, a short unbalanced 3.5 to 3.5 mm inter-unit cable, two clamps for fixing and mounting with a source, as well as instructions.
The amplifier is made in the form factor of a power bank, which is very convenient for such a device. Dimensions: 140x73x23. Weight: 325 g. The lithium-ion battery with a capacity of 4200 mAh is charged with a 15-watt unit in 3 hours. The working time declared by the manufacturer is from 7.5 to 12 hours. The material of the case is aluminum, one-piece design. The color is graphite gray. Discreet and elegant are the hallmarks of A&K devices.
The back has a textured silicone coating with patterns of straight lines intersecting each other (a usual Astell&Kern design variation) to eliminate the possibility of friction between the source and the amplifier – works great. The middle of the bottom face houses the USB Type-C port for charging the device. The front only has the brand logo on the bottom. The side edges of the device are bevelled. Classic complaints about the sharp edge of some models of A&K players, which sink into the hand, will not be relevant in this case. In the upper part of the left face there is a wheel on / off the device and analog volume control, which is large and slightly recessed into the case. Works neatly, smoothly and pleasantly.
There are three tumblers on the right side:
Current – regulation of class A current at three levels – Low/
Medium (+50mA)/High (+100mA).
Gain – adjustment of the output signal at two levels – Low (2.1 Vrms unbalanced, 4.2 Vrms balanced)/High (3.1 Vrms unbalanced, 6.2 Vrms balanced).
Crossfeed (turn on/off the crossfeed function).
On the upper face there is an LED indicator that displays the status of the device and the battery charge level, 3.5 mm and 4.4 mm input connectors and 3.5 mm and 4.4 mm output connectors.
Please note that headphones from the amplifier will work only if properly connected. When feeding a signal to the 4.4 mm balanced input, it is only possible to receive a signal from the 4.4 mm balanced output connector. When feeding a signal to the 3.5 mm unbalanced input, it is only possible to receive a signal from the 3.5 mm unbalanced output jack. There are no 4.4 mm in 3.5 mm out or 3.5 mm in 4.4 mm out scenarios. That is, the connection through the input and output connectors must match in terms of technical parameters. If the input and output differ in terms of technical parameters, the signal will not pass through the output connector.
Visually, the device is pleasant, practically unbranded, its dimensions are comparable to older models of Astell&Kern players (just a little thicker), during operation I did not find any noticeable inconveniences. The wheel and toggles are implemented coolly, random movements are not easy to achieve.
Let’s get to the interesting part. The amplifier is implemented in class A and it really heats up noticeably, as it belongs to an “honest” class A. It has great characteristics both in terms of power reserve and the quality of current amplification.
The PA10 delivers what you’d expect from a quality amplifier – great stage width with impressive edge processing, excellent dimensions and depth of images and instruments. Saturation of the musical picture, sound density and drive. Lots of drive.
The sound signature of the PA10 in many ways shows the Astell&Kern House Sound.
Complete delivery and rich sound. The amplifier produces an excellent amount of detail in recordings, but does not go into micro-detail, playing music, not sounds. The sound to a certain extent gravitates to the warm side with the highest quality performance. The amplifier has a slightly fat and very emotional tonal color, as well as a light warm background, without losing detail, separation of instruments and transparency of sound.
Bass is weighty, clearly designed, with good control and a neatly accented mid-bass. Since the lows are not dry, but have extra weight, they do not surprise with accuracy, but their impact, control and elasticity are at an excellent level. Despite all this, as befits a high-level device, the low frequencies are correctly positioned in space, do not interfere with the middle frequencies and do not distort the tonal balance.
The SC, of course, has the signature color from A&K. They are rich in timbre and competently inflated, with a beautiful filling. The amplifier highlights the vocals, gives them a charming physicality and makes them shine. The instruments played have three-dimensional penetrating images. There is a balance between low and high voltage, there are no dips and peaks.
HF are tinted. The main range of sound of instruments and electronic sampled sounds is expressive and at the same time (mostly) neatly soft for perception. Saturated overtones paint graceful surround decays with excellent extension.
The amplifier plays electronic music and live genres equally interestingly and confidently. Electronic music has the necessary dynamics, elasticity and richness of sound. The amplifier provides the necessary freedom, beauty, space and sound volume to live genres. Of course, the source and headphones used with the amplifier will play an important role here. But the fact that the amplifier is sufficiently diverse and universal is a fact.
It should be borne in mind that the amplifier is very sensitive to recording. In most scenarios, bad recordings will be embellished and sound very good, but the compression is read by the amplifier and passed on to the listener. Cool recordings give a cool sound at the output, very pleasant to listen to. The freedom of SACD is definitely felt. In general, the analysis of the operation of this amplifier with recordings is quite interesting and gives many answers regarding the potential of the device.
It should be noted right away that PA10’s high-quality amplification is more than enough. This device is radically different from the AK380 AMP and SP1000 AMP, so there is no need to draw analogies and parallels with these “spins”.
Moreover, I would like to note that PA10 with a balanced connection (I will remind you that the 4.4 mm by 4.4 mm cable is not included in the kit, when using the amplifier, balanced inter-block cables from Arctic Cables and Romi Audio and unbalanced from Alo Audio and Era Cables were used) coolly revealed Hifiman Arya SE. Better than any older portable player I’ve used, from the Ibasso DX300 to the Luxury & Precision LP6 TI 7th AE. The QLS QA390 (compare sizes!) has a comparable mastering quality with effort and control, but with the PA10’s richer tonality and Arya SE’s sonic signature, the A&K amp is more headphone-friendly and sounds more organic to my taste. That is, the PA10 has a very high-quality current amplification for its dimensions (which isodynamic headphones are very demanding), which even today is a problem for many devices in the portable segment (even the top line).
Sennheiser HD 800 from the balanced output are also mastered by an amplifier with a margin and play perfectly. Super demanding on gain quantity and quality, Tin P2 and Dope Audio Lucid in-channel planars are also at their best on this amp.
Although the amplifier has excellent gain and current controls, the PA10 does have a slight background noise with sensitive in-canal armature headphones. It is not audible when listening to music, accordingly, I did not experience any discomfort, but for some it is important, so owners of Solaris, Andromeda and other similar headphones are advised to familiarize themselves with the compatibility of their own headphones with the PA10 before purchasing an amplifier.
The crossfeed function is implemented carefully, clearly without overdoing it, but the degree of its perception by each individual person is a purely individual matter, so here everyone should listen personally.
The most suitable devices for comparison were not at hand, but to understand the capabilities and level, I will give a few conditional comparisons with those portable amplifiers that I had the opportunity to use in parallel. Comparing the PA10 with the ALO Audio Continental Dual Mono tube amplifier, it is safe to say that due to the specifics of the circuitry and tuning, the ALO device cannot compete as an amplifier with the PA10 in scenarios of use with full-sized headphones. PA10, due to much better current amplification, gives better sound density with the correct balance of frequencies and builds the scene more correctly. With in-canal headphones, the CDM confidently competes with the PA10 on equal footing, but the difference is very tasteful.
Phatlab Sassy GT with hybrid circuitry can handle full-size headphones no worse than the PA10. Personally, I prefer the Phatlab when used with dynamic headphones, the PA10 was a pleasant surprise when working with isodynamics (both full-size and in-channel) and mostly plays better with in-channel headphones.
In addition, the PA10 has much more convenient dimensions for portable use scenarios than the devices mentioned above.
Astell&Kern PA10 is an amplifier with great quantitative and qualitative indicators, which has a convenient form factor and a great size-to-power ratio. It has a bright, emotional, rich sound and is able to cope with the absolute majority of full-size headphones and, of course, in-canal headphones. It is practically as versatile as possible, behaves delicately and confidently in communication.
Can I recommend a new Astell&Kern amplifier for purchase? The PA10 far exceeded my expectations and I really enjoyed it. Considering the rather modest cost of the amplifier for this manufacturer, I did not expect anything special. But the device surprised with the level and nature of the sound. Knowing Astell&Kern and their pricing philosophy, you’d expect double the price for this kind of sound. I definitely recommend the amp for review. Whether you need extra power or want a new character, the PA10 is sure to impress everyone, including owners of the best portable players.