# Ear Evaluation# Advanced Experience Feiao K9pro Experience Sharing

in HIFI, there is always a chain of disdain, saying that those who play stereo don't like those who play big ears, and those who play machine big ears look down on those who play with them. From the perspective of sound performance, this may be the case, but there are different application scenarios in terms of convenience and so on, so I personally don't think anyone despises anyone. But then again, due to the energy limit of the portable battery, the power supply voltage limit and so on, the desktop computer with mains power supply always has the power advantage. Many friends around me also have many friends who always want to upgrade the listening experience from the previous desktop computer, but do not know how to choose. I hope I can have an idea and an alternative after watching my sharing.

More optimized operation experience

Feiao K9Pro actually seems a bit strange to me, because K9Pro came out before K9 came out. It can only be said that this year's chip shortage has disrupted the rhythm of many manufacturers, and the shutdown of AKM4499 has directly led to the development of the machine directly into a limited edition. Personally, I think K9Pro's thinking is very direct. Desktop-level all-in-one equipment, taking into account a variety of input and output devices, meets a variety of scenes used on the desktop, and can become the core equipment of desktop audio-visual entertainment. During the period when I borrowed the internal tester, I didn't use headphones too much because I was too busy. Of course, the experience and sound of this one I use are the same as that of the mass production version.

K9Pro is a small size in terms of the volume of the all-in-one decoder. This design is to reduce the occupied area of the desktop and better allow users to place the equipment. The pure aluminum cutting casing makes the overall weight 2.7kg, and the moving still feels heavy. K9Pro does not use the display screen, and uses indicator light to display input and ticker to display code rate to complete the display of working status. On the left side of the panel, there are three earphone output ports of 6.35mm, 4.4mm and 4pinXLR. In the middle is a volume knob with a light ring. On the upper right side, there are indicator lights of USB, optical fiber, coaxial, line and Bluetooth, at the bottom right are standby switch, input selection, gain selection (low Senior high school), output selection (DAC is used for external ear connector and independent front stage, PRE is front stage mode, adjustable volume is connected to active speaker and rear stage, HP is earphone output). The whole is simple and the operation is intuitive.

Behind is the power interface and output input interface, digital interface USB (there is also a TYPE-C on the side to connect to the mobile phone player), optical fiber, coaxial, Bluetooth antenna, analog input is standard single-ended RCA and balanced 4.4mm, output is single-ended RCA and balanced XLR. Generally speaking, it is relatively complete, but the digital input is not comprehensive without AES. It is not enough to use only a 4.4mm for balanced analog input. Personally, I feel that it is due to the limited volume. If I look at the design of the rear panel, I personally think Feiao prefers users to use K9Pro to connect various devices instead of using it as an earpiece.

In operation, K9Pro is more innovative in using Bluetooth connection to realize more operations. In FIIO control APP, the brightness and working state of the light ring (off, normal, gradual change) can be adjusted, Bluetooth coding can be selected, input source can be changed, filtering, equalizer, channel balance and timing shutdown can be adjusted, which makes me feel a little like using Q5S (laughter). Through this APP, the traditional decoding and ear-placing all-in-one machine can keep up with the times and operate more intuitively. This innovation is very interesting to me.

Experience

The K9Pro circuit board is relatively compact and focuses on the power supply part in the design. It is said that electricity is the mother of sound, and good power supply is the basis of good sound. In order to achieve good power supply, Feiao uses a linear power supply, uses an isolation transformer to isolate between analog and digital, and uses 20 LDO (low dropout Linear regulator) to maintain the power stability of each part of the electronic components, laying a good foundation for the overall sound to be pure and bottomless.

The digital part K9Pro uses XOMS 208 as the interface and clock management chip, and is equipped with two NDK femtosecond crystal oscillators (on the back of the circuit board). It uses asynchronous reception when USB and Bluetooth input, and uses self-calibration phase-locked loop when coaxial optical fiber. From this design, Feiao pays more attention to USB input. Coaxial and optical fiber are greatly affected by the front-end turntable. It is a pity. The decoding chip uses AKM4499. This chip is not the focus of my attention. I pay more attention to the four large decoupling capacitors behind the chip. The decoupling capacitors exist to separate DC and AC and protect the chip from clutter interference in power supply. Personally, I think the use of large decoupling capacitors is also a mark of distinction between machine and portable design. Both I/V and LPF use OPA1612, which is a conventional decoding configuration. The coupling capacitor uses a machine-scale capacitor (WIMA thin film capacitor) like the decoupling capacitor. In the whole digital part, the clock management for coaxial/optical fiber signal input is the more slot point, which has to be said to be a small pity.

Advanced Experience

From the results of my personal use, I personally think that K9Pro is committed to optimizing two things besides the use of general all-in-one machines, one is compatibility with earplugs, and the other is the previous level. In terms of sound, this is an all-in-one machine that pays great attention to clean and delicate sound. On the whole, the sound field scale is large enough, the quality is high, and the thrust is full, which can meet the general use. The low frequency of K9Pro is of very good quality, diving and cohesion are very good, boxing to meat, diffusion feeling is slightly poor, I think it is to create a clearer low frequency junction image, the intermediate frequency is slightly backward, the junction image is relatively large, it is not a routine of stacking to the intermediate frequency density, it adopts the method of correctly restoring the position relationship of the general machine, positioning and alignment, and achieving high separation and accurate positioning in the loud field, the information is full and not empty, the high-frequency energy is sufficient, the brightness is good, the whole is round and not stimulating, and of course it is not as strong as the air sense and high-frequency attenuation naturalness of high-end machines.

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There are few desktop decoding and earplug all-in-one machines to pay attention to the needs of earplug users. My desktop earplug is not suitable for earphones with an anti-group of less than 20 ohms (actually using 32 euros is barely enough). If you are an ordinary user and have a lot of earplugs in your hand, wouldn't it be a waste to buy an all-in-one machine? The output resistance of K9Pro is below 1 ohm (the balance is about 2 ohms), which can be adapted to resist the resistance earphone, while taking into account the large earphone. The medium and low gain working voltage of the gain setting is 10V to prevent the low resistance earphone from overloading; The high gain working voltage is 15V, and the optimized volume curve can also ensure the driving effect of the big ear.

In my personal experience, I am more in recognition of the driving effect on earplugs. When driving earplugs, the sound is full and the sound field scale is very large, which does not make people feel impulse or stimulation. I have personally matched FIR M5 and IE800S, but not with moving iron headphones. I am especially satisfied with the performance of IE800S and have obtained the driving effect that has not been achieved with me. Compared with M15, I have incomparable advantages in both three-frequency fullness and sound field scale. Especially when listening to the popularity, the fullness of the intermediate frequency is very good. It has to be said that the power supply advantage of the machine is the absolute advantage to push forward the intermediate frequency that M15 cannot be filled. FIR M5 has tried to drive on the bile machine before, so it is also safe to try on K9Pro. This earplug has great potential. Personally, I feel that the sound performance has not lost the ear earphone in terms of sound.

The driving effect of the big ear depends on the earphone. The driving HD700 has achieved excellent results, and the sound completion is extremely high. Both the amount of information and the sound field have very good performance. On HD800S, it is obvious that the driving force is insufficient, the sound field is squeezed, the intermediate frequency fullness is not enough, and the image is not clear enough, but it relies on good high frequency performance, HD800S is used to match children's voice with low requirements on the knot image. When matching with Jinwu, you will obviously feel the lack of sound resolution, but the good intermediate frequency density makes up for the lack of K9Pro, making the sound intermediate frequency performance very good.

From the point of view of the computer's earphone port playback, I personally recognize K9Pro's compatibility with earplugs and the low and medium resistance non-flagship big ear drivers. Personally, I cannot require a decoding all-in-one machine to drive the flagship earphone at the same level as the home split system. This requirement itself is very harsh and unrealistic.

In addition to local playback, K9Pro also has pre-stage mode and DAC mode to choose from. In DAC mode, I connected 430HA to drive HD800S and got very good results immediately. This is due to K9Pro's excellent decoding design, especially the low frequency quality is very good. It is obviously turned on under the sound field with independent ears down, and the sound density has no virtual feeling (after all, it is a high level output of 5, however, the sound details are relatively flat and lack of freshness. This is also the other side of low-cost decoding that emphasizes analysis and quality. Of course, this is a comparison with the decoding I usually hear. I always compare what I am used to listening to. Personally, I feel that this can fully guide its advantages and better realize its shortcomings. After all, as long as it is a device, there is no perfection.

ear release mode is more like an attached (input option LINE) to me. Although there is a standard RCA interface for single ends, the balance intervention only gives a 4.4mm interface. Probably because Feiao has only M11PLUS balanced LO (what about M17)? According to the input of desktop decoder and bricks, K9Pro is indeed more suitable for LO of bricks. The effect of better desktop decoding (MSB ANALOG) lacks support for decoding information. Compared with high-end earphones, the sound is more squeezed. In the case of bricks, the sound becomes more comfortable and can be coordinated, but it is still not as good as playing on this machine. From my point of view of use, I didn't use headphones too much because I was too busy during the time period when I borrowed the internal test machine. Of course, from my point of view, it is a bit wasteful to connect a decoder better than K9Pro to K9Pro, but not as good as the brick connection of K9Pro, and a waste of decoding of K9Pro itself. It also reflects from the side that the ear placement part of K9Pro is more suitable for this machine.

In the front-level mode, you can directly connect the active speaker and use it as an audio-visual center on the desktop. I connected the rear-level push speaker and got a very good effect. Generally speaking, K9Pro also has the advantages of complete functions, good sound coordination and high completion, and can be adapted to a variety of equipment and playing methods.

Everyone is looking forward to a better experience, especially when the calm of mobile battery power cannot be broken through, desktop equipment has become a choice for improvement. A front-end that fits the device at hand, is compatible with multiple usage scenarios and has some spare capacity to take care of future upgrades is attractive to many people. If you want your headphones to perform further, or if you have friends who need desktop multimedia audio and video, you may as well experience K9Pro, which can make the experience further, whether it is to improve the expressiveness of headphones or to meet the needs of multi-purpose purposes.

author:chen_racon202109-27 13:19

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