Review and Disassembly of the K9 AKM (a different core): Desktop DAC and Headphone Amplifier
The AK4191+AK4499EX chip set was first applied in FIIO's product lineup with the portable DAC and headphone amplifier Q15. The Q15 is a remarkable product, excelling in performance and durability.
Since the AK4191+AK4499EX chip set has already been successfully implemented in portable devices, it's a natural progression to move towards desktop-level products with a larger body and more abundant power supply. The previous model of the K9 used the ES9068 chip. Due to its modular design, it was quick to transplant the new decoding module without major adjustments to the motherboard, leading to the introduction of the AKM chip shortly after.
"Figure: The AK4191+AK4499EX chip set has been applied in the Q15 portable DAC/Amp."
The AK4191+AK4499EX belongs to the VELVET SOUND product series, which is AKM's digital/analog dual-chip separation decoding solution. The DAC is a crucial component in the digital audio chain, and splitting the conventional single decoding chip into functional units encapsulated in two chips, allows for a higher upper limit and more possibilities in this process.
In fact, this also pays homage to the classic Philips solution, returning to the roots in terms of paradigm. The historical content about this aspect was discussed in the previous Q15 review.
Here, AudioTOP also predicts that AKM may continue to focus on the chip set, going further and producing more digital and analog modular units to facilitate the creation of rich chip sets.
In addition to changing the core of the internal decoding circuit, there have also been some minor adjustments to the I/O ports on the body. The original K9 had a USB Type-B input port on the rear panel, while the K9 AKM version added a USB Type-C port on the right side of the body.
Both the type and position of the new port are evidently more user-friendly for mobile audio sources like smartphones. In actual use, the insertion and removal feel smooth and effortless. Previously, to connect a smartphone to the Type-B port, you had to prepare a corresponding OTG cable, and it is difficult to find one with high specifications.
The convenience of the position goes without saying. Every time you access the ports on the back of the body, it's like groping in the dark. Now, with them placed on the right side, access is effortless. Even for left-handed users, it's easy to use the K9 AKM by simply standing it up.
Although it's a core change, it's still a small action, so the difference in sound between the ESS and AKM versions of the K9 is not very significant. The headphone amplifier section of both versions is the same, thus to some extent, this mitigates the differences brought about by the decoding circuit.
Through repeated ABBA comparisons of the same tracks, it can be heard that the AKM version has slightly lifted vocals and instruments, making them more transparent. In comparison, the ESS version has a slightly stronger sense of bass.
In terms of timbre, the ESS version is straightforward, while the AKM version is slightly embellished, thus providing a slightly better listening experience with a velvety texture.
AP testing results came with the signal acquisition channel being the headphone jack. The test data for both the old and new versions of the models are decent and difficult to distinguish. In terms of headphone output power, since the headphone amplifier module has the same specification as the old version, the overall indicators are more or less the same.
In terms of noise, crosstalk, distortion, and other aspects, the new version has slightly improved due to the new decoding chip's superiority. Other minor discrepancies can be attributed to measurement errors.
The disassembly started with the rear panel.
Power socket.
Bluetooth antenna.
After unplugging multiple cables and removing the bottom panel, the internal circuitry can be pulled forward.
The thickness of the main case is considerable, measuring about 6 millimeters.
An overview of the internal circuitry of the main body.
A custom transformer with a logo.
The power supply is also protected by an acrylic cover, which is actually part of the framework.
Decoding module, AK4191+AK4499EX chip set, somewhat hard to see through, right?
The back of the headphone amplifier module, one for each channel.
The front of the headphone amplifier module. This side is blocked by the heat sink.
You heard all k9 and many other fiio and i see you liked it if you listened it so long, will wait your further impressions but from this short notes i believe it is worth the price and is good sounding device.
