listening to music with it can spoil ears, the double AK4499 decoded Feiao M15 evaluation has come.

on December 28 last year, that is, after the launch of Feiao's new winter products, I got the M15 evaluation prototype. At that time, I listened to it briefly with the FH1s headphones released together, which was a great surprise. Since the Jade Audio version EA3 of FH1s has been reviewed before, it can be inferred that the sound quality level of M15 is much higher than that of M11 Pro, which is definitely worthy of the title of Feiao flagship. How good is the sound of M15, or what is the sound quality level of M15? Let's look at this article's graphic evaluation of M15.

, due to the increase in selling price, Feiao finally upgraded the product packaging, which is completely two grades from the past. Just looking at the outer box, I dare not say that its temperament is close to the price range of 10,000 yuan, but when the first layer of box is peeled off, what comes into view is full of the smell of "RMB.

The inner packing box made of black walnut wood in North America has a good ornamental value. The taste of logs can be smelled faintly. The surface is only polished, without paint or any other superfluous treatment. It gives people a feeling of natural nature and is very close to nature.

this is what the wooden box looks like, the style is also concise. Moreover, only one M15 player host was installed in this small wooden box, which I had never thought of before and overturned my inherent impression of Feiao flagship.

you're not wrong! There are no random accessories in the wooden box of M15, just a player host. In fact, Feiao has developed many accessories for M15, including SK-M15 official protective leather case, HB4 storage box, DK1 Type-C base, LA-UA1 car isolator and LT-TC1 double Type-C USB cable. These original accessories have become a large gift bag worth 800 yuan independently. You need to get the list free of charge after purchase. I really don't understand the divine operation of Feiao, and it is said that the first batch of original spare parts gift bags will not be sent out until after the Spring Festival.

switched to Samsung's development platform, Feiao's new speed is getting faster and faster, especially the middle and high-end new speed, one followed by one. This is one of the reasons why Feiao was able to successfully launch the M15 player at the end of 2019, and another reason is related to Japan's Asahi Kasei's frequent exposure to learning AK4499 decoding chip development technology more than a year ago. The development of M15 has received strong support from Asahi Kasei China. It can be said that without Asahi Kasei's full support, there would be no M15 player. In contrast to today's portable HiFi industry, apart from Astell & Kern SP2000, the only player product using AK4499 × 2 top decoding scheme is Feiao M15.

Before introducing Samsung Exynos 7872 processor platform, Feiao used Fuzhou Ruixinwei's RK3188 processor platform. Stability is also acceptable, that is, the power consumption is relatively large, especially the standby power consumption. As long as I don't listen for a short time, I will shut down manually. It was not until the emergence of M11 that Feiao completely solved the problem of high standby power consumption, and the system was stable and smooth. It is also among the best in the field of players.

no accident, Feiao M15 still uses Samsung Exynos 7872 platform, 2 4 large and small core design, two large cores A73 dominant frequency up to 2.0GHz, four small cores A53 dominant frequency up to 1.6GHz,14nm process technology, built-in Mali-G71 GPU unit, overall can take into account higher computing performance and ultra-low power deep sleep standby. 3GB storage is enough for music players. After all, there is no need to install many apps. At most, there are three or two commonly used online music apps. In terms of storage, M15 has 64GB of built-in space, and there is also a TF card slot, which supports up to 2TB expansion.

two-way Type-C interface has long become the standard of Feiao middle and high-end. Unfortunately, USB transmission is still 2.0, and it will take some time to fill up 64GB of built-in storage space. M15 on wireless connection supports Bluetooth 5.0 and dual-frequency 2.4GHz/5GHz WiFi. In addition, it also supports QC2.0, PD2.0 and MTK PE protocol fast charging, with a maximum charging power of 21W. The battery life of playing CD-grade music can reach 15 hours, and the battery life of playing higher code rate or DSD is slightly reduced. By the way, its built-in battery is a 3.8V high-voltage lithium polymer battery with a capacity of 7490mAh. This is the maximum battery capacity in my memory. The power consumption of the two AK4499 decoding chips is really not low.

the design concept of full screen, the proportion of screen is definitely not comparable to the current full screen mobile phone. 5.15-inch capacitive touch screen, Corning Gorilla Glass, 1440 × 720 pixel display resolution, the image quality is still very fine. In operation, you can select the virtual key mode on the photo or the full screen sliding mode.

Except for the volume knob, all the operation keys are concentrated on the left side of the host. Here is an unmarked key. It is a custom key. It can be set to add the currently played song to the favorite, randomly jump to the next song, switch EQ, switch filters, enter USB decoding mode, and so on. Personally, I like to add to favorites by default, so that I can collect my favorite songs in the same playlist. In addition, there is a HOLD switch. Sometimes when you put the player in your bag or pocket, you will accidentally touch the key, especially the volume knob. It is good to reduce it by mistake. If you increase the volume by mistake, it will hurt both ears and headphones. Therefore, this HOLD key is very necessary. In the system setting menu, we can also separately define which keys the HOLD key work on, which is very humanized.

has a complete output interface configuration of 4.4mm balance, 2.5mm balance and 3.5mm single end. The three interfaces on the M15 unify the design style, and the center of the circle is made on the same straight line, including the center of the volume knob, so the vision is more neat and beautiful.

And for daily desktop use, the three output interfaces and volume knobs are all at the top of the host, which does not hinder normal operation when M15 is placed on the base.

M15 is a traditional analog potentiometer adjustment method, and some professional players like to be close to traditional things. Different from digital adjustment, the volume cannot be automatically reset every time the computer is turned on. Although some protective measures have been taken on the system side, I think it can be more rigorous in actual use. For example, the volume is forced to be manually screwed to the minimum and then reset after each headset is replugged and unplugged, and when the volume is turned in half, it is best for the system to give a pop-up confirmation reminder.

, let's talk about decoding, which is also the most important part of a professional audio player. First of all, the AK4499 decoding chip has a very high parameter index. A single chip has 4 decoding channels, but HiFi only uses one of them. Stereo requires a total of two AK4499s to improve the signal-to-noise ratio. The AK4499 signal-to-noise ratio at single channel is as high as 140dB, which is a very scary number. Of course, after the signal undergoes a series of conversion and amplification, the final output signal-to-noise ratio is impossible to be so high, but the signal-to-noise ratio of M15 is greater than 118dB under 32 ohm impedance, especially considering the output power of M15 (PO up to 490mW/balanced up to 800mW under 32 ohm impedance), such signal-to-noise ratio performance is absolutely difficult to meet.

this is a diagram of the decoding principle of M15. It can be seen that the digital signal is converted by AK4499 and adjusted by four OPA1612, followed by two OPA2211 for low-pass filtering, and then four OPA1622 for amplifying and expanding the signal respectively.

has XMOS XUF208 USB decoding chip, CSR8675 Bluetooth decoding chip, two femtosecond crystal oscillators of NDK (whose phase noise can be as low as-140dBc/Hz), and the third generation FPGA developed by Feiao, which are all top-level matches, worthy of AK4499, the top-level audio decoding chip at present.

all say that Feiao likes stacking materials. This time, he really brought the stacking materials to the extreme. For example, the audio circuit used 4 high molecular tantalum capacitors, 4 Panasonic stepless film capacitors and 8 small film capacitors. The power supply part uses 28 220uF polymer capacitors and 5 100uF high voltage capacitors. The low-pass filter circuit part adopts 4 independent designs, sharing 8 Panasonic metallized film capacitors. In addition, there are 8-layer PCB boards with gold sinking process. In the past, the same type of products were at most 6-layer PCB. The production process is relatively simple, and 8-layer PCB is still quite difficult. The advantage is to improve the space utilization of PCB. In addition, the analog circuit and digital circuit parts of M15 are designed with shielding covers, and the interior is also coated with absorbing materials to avoid mutual interference of components. AK4499 has a large calorific value, so M15 uses thermally conductive silica gel, graphene and cupronickel heat sink to effectively conduct the heat to the shell of the host. After using M15 continuously for half an hour, you can feel obvious heat on your hands, but it has not reached the level of ironing. I have only seen the picture of the official leather protective cover, and there is a large heat dissipation window on the back, so there should be no problem in wearing the original leather cover to use heat dissipation.

audio file formats has long been a problem in the national brick, but any music format can make a sound. However, in addition to full format decoding, M15 also has MQA 8 times open capability, which is rare, and supports DSD512 hard decoding natively, while PCM decoding is as high as 32bit/768KHz, and USB decoding can also support 32bit/768KHz specifications, which is very tough.

and the Bluetooth function of M15 is also "flagship". SBC, aptX, aptX-HD, LDAC, HWA can be emitted, and SBC, AAC, aptX, aptx-LL, aptX-HD, LDAC can be received. Basically, it can be regarded as full-format Bluetooth support. M15 has four modes of listening to songs, namely, Android mode (running and installed APP), pure tone mode (only Feiao Music APP can be used to listen to songs), USB decoding mode (connected to PC or other USB turntable), and Bluetooth decoding mode (bidirectional Bluetooth can be connected and sent). Personally, I basically use pure tone mode at ordinary times, and only enter Android mode when upgrading firmware.

the original output power of M15 is large, but in order to adapt to larger impedance headphones, M15 also has a big ear mode, which is mainly designed for 300 ohm high impedance headphones. In big ear mode, the 300 ohm impedance PO output can reach 70mW of power, while the balanced output can reach 280mW of power. In addition, low-resistance earphones, such as 32 ohm impedance earphones, have a maximum power of 490mW for PO output and a maximum power of 800mW for balanced output. From the aspect of earphone adaptation, M15 has achieved broad compatibility from low to high. It can be said that an M15 player is in hand and can walk sideways outside the home.

judging from the decoding schematic diagram, the single-ended output sound quality of M15 is definitely not as good as the balanced output, and the actual hearing feeling is indeed the same. For this reason, I also had in-depth discussions with several senior enthusiasts, and the results were the same. The difference is that some fans think that the sound quality of the M15 balance port is too much beyond that of a single port, so that only the balanced output can show the real strength of the M15. However, my view is slightly different. The single-port sound quality of M15 itself is also remarkable. However, when pushing headphones with lower sensitivity, the single-port sound is not as full as the balance port, with a slight difference in density. The size of the sound field and the distribution of the three frequencies are basically the same. If high gain is used for single-port output, this gap will be further narrowed. The difference in sound density at low gain depends mainly on headphones. My ears don't sound so outrageous. If quantized by numbers, the average balanced output of different combinations is assumed to be 10 points, and the single port is above 9 points.

, my first ear was moved by its beautiful voice. The sound details were close to perfection, the edges and corners were extremely clear, and the three-frequency quality was excellent. It seemed that I had returned to the feeling of X7 era. The difference was that M15's listening feeling was much better than X7. Its voice was soft and flexible, and its listening was especially smooth. I remember that before the AM3A ear module came out, the X7 sound was dry. The quality of Senior high school low frequency was actually good, but the listening feeling was not natural enough. While M15 has further improved its three-frequency hard quality, it has focused on solving Feiao's imperfection in listening. This time it is really difficult to pick out the sound problem on M15.

simply describe the hearing feeling of M15? I thought of QDC chameleon headphones, which are really different types of products of the same number. First of all, it's hard for you to find faults. At least in the ten days I used it, after countless headphones, I still couldn't find obvious shortcomings. Secondly, the personality of the sound is too stable. No matter what headphones are plugged in, the unique charm of M15 can be recognized. The timbre is very stable and the control is good. The third is that it is especially resistant to listening and easy to listen to. On the afternoon of January 3, I accidentally picked it up and listened to it for a while. The more I listened, the more fascinated I became. I listened to it unconsciously for more than four hours. I only used FH1s headphones, which was simply too cool. After taking off the headphones, my head hurt for a long time, the volume was too high, and I was not suitable for wearing in-ear headphones for a long time. Since then, I have been very restrained, protecting my hearing and ears. After all, I have to rely on this for food in the future.

M15 is very open, but there is no exaggerated component. The restoration of the recording environment is in place, and the accurate positional relationship between instrumental music and human voice can be imaged in my mind. As long as you pay a little attention to every piece of music you have heard, you can hear the location of the studio microphone at that time, and even the distance between the singer and the microphone. However, the accompaniment of the mixed sound is obviously different from the lyrics on M15. It sounds different from the three-dimensional sense of space, and the natural nature of off-site accompaniment is natural. I think M15 can be used to feedback the production level of a record. I have tried a lot and it is worth pondering. This also shows from the side that M15 has some sound performance capabilities that are unique to desktop computers.

, let's talk about the low-frequency performance. The elasticity and diving depth are excellent. In addition, the low-frequency of M15 has some toughness. It sounds special as a whole. The overtones of low-frequency rebound are very textured and cohesive, as if they want to achieve the bass quality of the box on the earphone. However, the performance of human voice is relatively direct, basically without any polishing. The quality of the original document is good for good voice performance. If the original document is compressed badly, the performance will be average, so it has nothing to do with such things as female poison. The high frequency is also the first-class level in the portable range, and the analytical power and extension are just right. However, due to the fullness and density of details, the high frequency saturation is higher, and the hearing feeling will be more exciting and easy to be emotional.

, as far as sound quality performance is concerned, taking the portable player products on the market as a reference, the sound quality level of M15 is definitely above 10,000 yuan, but the brand of Feiao is really almost meaningful. After all, it is done step by step from the beginning of the fever. The brand is seriously short of premium ability and naturally dare not price according to sound quality performance. Therefore, M15 is more suitable for those enthusiasts who have no forcing requirements for the brand and just want to enjoy excellent sound quality performance.

should have ended, but suddenly remembered M11 Pro, just a few more words. Here only talk about sound quality, the gap is really quite big. Only one or two pairs of earphones will not feel very deep. The more you try, the greater the gap will be. The principle that you get what you pay for is very appropriate on M15 and M11 Pro.

has talked here, I 'd like to say a few more words about Astell & Kern SP2000, which uses the same decoding chip. I 've heard the sound of SP2000 twice. By memory comparison, the sound quality of balanced output is equal to that of M15, and the quality of single-ended output SP2000 is slightly superior. Considering the selling price of SP2000, it cannot be described here as a penny for a penny. After all, Astell & Kern set the tone from the beginning to be high-end and top-notch.

, use this M15 and M11 Pro volume wheel comparison chart as the end of this text, because I really don't like the M15 volume knob design, which may be the only place where I am dissatisfied with M15.

author:Forever YC01-10 21:29

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