$110 (discontinued)

This one slipped down the publishing schedule, my bad, but it is rather good timing considering we just published the DK1 Multifunction dock a few weeks back which offers a slither of what the K5 can do with the X Series of DAPS and the E17k from FiiO. This time, instead of the DK1 $20 asking price for essentially a stand with a line out and charging, you get a $110 ticket price for a whole lot more.

Those who have been following FiiO since the early days will recognize the K5 as a 3rd gen amp/pass through DAC dock system that first started as the E9 in 2010. Back then the whole concept was to stick in your E7 DAC/Amp as the DAC component, turn it on, stick in the USB cable at the back of the E9 and bingo! You have a mini DAC/Amp system capable of some decent power and a better signal than what the E7 was ever capable off. It looked very cool and for budding audiophiles on a budget, it was considerably good value. The E9K, launched in mid-2012 was essentially a tweaked version of the original. In came an enhanced I/O array at the back, a better 3.5mm jack impedance output, and a more integrated power management facility to control both the E17.

The E9K, launched in mid-2012 was essentially a tweaked version of the original. In came with an enhanced rear plate I/O array, a single quarter jack output, and a more integrated power management facility to control both the E17 and the E9K at the same time. The basics were the same, the amp chips the same. For a device of its time, it was a perfect match for FiiO’s old portable DAC line.

What Is The Pitch?

The FiiO K5 makes a pitch now with the same docking principle of the old E9 series but this time thoroughly updated to match and support their current line of X-series DAPS with DAC functionality including the X3ii, X5ii, and the X7 (with amp module) as well as the E17K. It pretty much does everything that the DK1 does but throws in an amp stage, some gain options and some dedicated RCA I/O at the back as well as a balanced line out.

The amp itself is considerably more powerful than anything the X Series DAPs and the E17K can produce, even with the AM5 module so this should be seen as a desktop amp and DAC solution aimed for those with desktop mid-fi or more power hungry headphones that require a bit more juice. If you do not need the amp or do not need the juice, then the modules on their own or the DK1 will be better solutions.


Much of the legacy of the E9 remains true in the new K5 despite its more modern lines and slight physical repositioning of its switches and dials. It is now a 30mm shorter, 35 mm wider and the same 55m in height. Much of that expansion in girth has to do with the large dock port bay on the top that is design to hold the varying widths of the E17k/X3/5ii and the X7 as well as the additional switches on the front panel. The chassis is a little more rounded on the K5 and the quality of engineering has improved with the naked panel screws of the E9 now nonexistent on the integrated plating of the K5.

The Dock

The top panel is flush with only the dock port lid interrupting the smooth lines of the metal chassis. The dock port is a self-contained articulated lid and bay system with an interconnecting male micro USB socket for receiving and communicating with the X-series DAP of your choice once connected. The lid itself has a degree of swivel just like the DK1 so it can adapt and support the DAP correctly. The K5 also comes with a set of rubber tips that can be inserted into the back of the K5 dock lid. This helps support the differing sizes of the X-series DAPs and to prevent inadvertent scratches during use.

Front Panel

The front panel has a few changes also. The pot is still centered much like the old E9 and E9k but the wider front panel is now able to accommodate not only the old input switcher (line and dock on the K5) but also a new 3 level gain control system (low, medium and high) offering greater flexibility for today’s range of efficient and non-efficient headphones. This is compared to having only 2 gain options (high and low) at the back of the E9k. To all extents and

The volume range of the K5 is the same as the E9k starting at -90dB but this time the power on LED in the lower left corner has been upgraded to a backlit pot LED which looks all the more handsome and striking when turned on. It almost matches the same blue lit panel of the X7 but just a touch more turquoise to it. The right side of the front panel is again finished with a quarter jack gold plated socket.


Back Panel

The back panel houses the majority of the inputs in terms of line in, USB in and proprietary dock in functionality as well as the AC power. It also houses the line out and a dual 3.5mm balanced output for those wishing to build a fully balanced system with another amp of differing specs. Technically FiiO has actually slimmed down some areas from the old E09K back panel. Gone is the old aux and pre-out dual RCA and in its place is a dual RCA line and a dual RCA line out in unbalanced mode.


The FiiO K5 actually has quite a wide range of useful applications for the asking price. Some of them do overlap with other complementary devices such as the DK1 however the K5 is the only such support device that offers built-in amplification for headphone use for the X Series. The various methods of connectivity and usage of the K5 are as follows:

  1. Standalone dock and amplifier combo using the X-series DAPs (X3ii/5ii/X7) as both DAC and storage for music files and connecting directly to your headphones
  2. USB out from your PC/MAC into the K5 using the X-Series DAP and E17K as your DAC and amplification directly to your headphones
  3. Line out from your existing DAC setup using the K5 dual RCA line in and K5 amplification direct to your headphones (could be 3.5mm single line out to dual RCA K5 line in also if using a DAP as your DAC)
  4. USB in (E17K) or docked X-series DAP with single ended dual RCA line out to amp of your choice
  5. USB in (E17K) or docked X-series DAP with dual 3.5mm balanced output to XLR/3.5mm balanced headphone or stereo amp of your choice
  6. Secondary dock in (allowing points 1, 2, 4, 5 ) functionality for docking an X-Series DAP or E17K without using the top docking plate
  7. X-Series DAP and E17K charging while AC Power is on.



The K5 uses a Texas Instruments TPA6120A2 powered amp stage which is a right old age now and came out around 2010. In actual fact, I guess FiiO quite love this amp stage because it is the same chip that can be found in the original E9 and the tweaked later 2nd Gen E09k. It’s not clear to me if the K5 is still using an OPA2134 opamp alongside the TI buffer chip but given they didn’t change the buffer chip I presume they didn’t change the opamp either.  The TI Buffer is generally known to be capable of producing high levels of power, with low distortions levels and more than capable of projecting a wide bandwidth. I guess if it’s not broken don’t fix it?

The important difference though between the older units and the K5 is the nominal output impedance is much more acceptable at less than 1 Ω compared to the almost 10 Ω rating of the original E9 which made it less appealing to those with low impedance headphones. This time, the design is more attractive to those with efficient portable headphones and earphones who are looking for less play in their stock frequency response though the power rating might be a bit too much at 1.7W into 16Ω.

The original E9 amplification was also lauded for excellent low-level distortion performances with the TPA6120A2 and I expect no difference with the new K5 design, perhaps even better ratings.


Page 2: Sound Impressions

The K5 By FiiO
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