[General Accessories] vectron:
This is a Review of FiiO K5 Docking Amp. http://fiio.net/en/products/46, available on Amazon http://www.amazon.com/gp/product/B01BBX1NNM/?tag=vectron00-20

Can you refer to a docking desktop amp as “jack of all trades”? You certainly can when you start playing with FiiO’s latest K5. Prior to receiving it, I was expecting K5 to be a desktop accessory for X7 only. But was I wrong! In addition to being compatible with FiiO’s latest X-series DAPs (X1/X3ii/X5ii/X7) and their E17k DAC/amp, it can also work with other audio sources connected to RCA Input, and even take advantage of DAC processing inside of a docked DAP while feeding audio from your laptop. After spending over a month with it, here is what I found.

Unboxing & Accessories.

Arrived in a sturdy cardboard packaging box, I like how FiiO choose to have an all black background with a glossy image of K5 and a docked X7 popping out in “3D” from the front cover. All the promotional pictures of K5 I’ve seen featured X7, but make no mistake – it’s intended to work with other FiiO X-series DAPs. The back of the box has a detailed spec, including a very impressive output power rating for such a compact desktop amp.

Before opening the box, I did take a notice of the weight since we are dealing with an amp, though later turned out that part of it was contributed by external power converter. Once taken out, you can feel that the actual amp is not that heavy at 450g, packed into 120mm x 130mm x 55mm compact enclosure. The power supply converter is external, a typical AC/DC supply with 15V/1.5A output you can find with a number of laptops. As a matter of fact, my review unit arrived with non-US plug and FiiO kindly included an adapter which got temporary misplaced, so I ended up using power converter from my old Thinkpad.

Other included accessories were 4 rubber bumps/feet, 2 insert adapters for different DAPs, usb cable (full size usb-B to usb), 1/4” headphone adapter, and a user guide. Considering a number of all the inputs and outputs, it would have been nice to see other cables included with accessories, for example a pair of RCA to 3.5mm cables or 11pin micro usb connector, and maybe balanced 3.5mm cables. Of course, these extra cables are not a showstopper to get you going, but still would have been great to see at least FiiO’s proprietary 11pin micro-usb interconnect cable. The docking can only accommodate X-series DAPs without a case/skin, and you need to use this extension cable connected to “dock in” micro-usb port on the back of K5 if you want to keep your DAP dressed.

Accessories.

Design.

Since I’m into portable audio gear, I rely mostly on standalone DAP use, though have one desktop amp and a handful of portable amps. In my opinion, K5 design fits somewhere in the middle. It’s obviously a docking amp designed for a desktop use, but it doesn’t weight a ton especially since power supply is external to the case. It’s lightweight, but still has a solid build with a nice titanium color aluminum shell. It has a relatively small footprint that not going to occupy too much space, and yet it is sturdy enough on a flat surface. As a matter of fact, I dragged it next to me on a couch and had no problem using it even so the surface wasn’t perfectly flat. Ergonomics of the design and tight fitment and placement of the micro-usb connector contributes to a nice weight distribution without anything tipping over, even with X7 docked.

With K5 being a “docking” amp, the key feature of this amp is micro-usb docking port on the top under the flip panel. When not in use or using external ports, the panel is flush with a top surface with an exception of a small tab to open it up. The flip panel mechanism is smooth and the panel turns into a solid back support of a docked device when flipped open. Inside you can see a pocket to cover micro-usb connector when it’s closed and another elongated pocket for a rubber adapter to accommodate different DAPs, depending on thickness variation.

The main focus of the front panel is a large rotary volume knob that also functions as a power switch once you turn it clockwise, greeting you with a brief red backlight glow while it initializing and then turning blue. I absolutely love this detail which matches X7 blue light for a visual feedback when power is on. Turning the power on will also turn the power on X1, X3ii, X5ii, X7, and E17k, and the same when you turn it off, though you can dismiss power-off from the DAP screen. And with power on, your DAPs will also be charging. The knob is big, yet easy to grip, has a perfect potentiometer resistance for a better control of the adjustment, and a clear white marker indicating rotary position which goes from -90 dB to 0 dB.

The front panel (the same as a back panel) is slightly recessed with a nice bezel trim design, and you can find to the left of the knob Input switch for Dock vs Line selection and Gain switch for Low (0 dB), Mid (6 dB), and High (12 dB) gain setting. Input switch will correspond to a source selection of either DAP from the dock (or micro-usb “dock in” port) or the Line input. In High Gain you can drive your HO output with a VERY impressive 1.5W (32 ohm load) power which scales down to 150mW (300 ohm load), and most likely with enough juice to drive your 600 ohm cans. I found these flip switches have a nice click action. To the right of the knob you will find 1/4" headphone output, keeping in mind that 3.5mm adapter was included with accessories. I was happy to see FiiO didn’t clutter the area around HO with switches, keeping it clean.

The back panel of K5 reveals a Power in connector jack for 15V supply, all the way to the right, and a number of additional connection ports. You have usb-B USB IN connector for digital input from your computer while processing a signal through X3ii, X5ii, X7, or E17K internal DAC, DOCK In input for 11pin usb interconnect cable if you can’t dock your DAP (due to case/skin), a pair of RCA Line In and Line Out connectors for external input connection from any audio source and to other audio source inputs, and Balanced Line Output. This dual 3.5mm Balanced Line Out output can be used only in conjunction with X5ii or X7 to connect to another external amplifier stage.

Sound Analysis.

While testing K5, I focused on 3 main pair up scenarios with docked DAPs, external connection from LO of the DAP, and digital input from my laptop. In every case I found K5 as an amp to be rather neutral, transparent, and contributing to a noticeable soundstage expansion (especially in width).

Of course, pair up with X7 was at the top of my list. By default, this flagship DAP from FiiO comes with IEM amp module which does a good job with in-ears and other efficient headphones, though I have to keep it in high gain. K5 pair up really stepped up X7 performance with a deeper sub-bass, more organic mids, and additional sparkle in treble - a very consistent improvement I found across R70x (470 ohm) and both planar magnetic PM-3 and EL-8C. Another change was in soundstage expansion, in all three dimensions of width/depth/height where width was the most noticeable. I can't judge yet how other X7 amp modules going to compare, so keep in mind this is relative to IEM module.

Docked with FiiO other DAPs, I found X3ii + K5 pair up to make sound more transparent, with a slightly improved dynamics and expanded soundstage, and with X5ii + K5 a found more body in lower mids giving sound a little smoother organic tone, and also the improvement in soundstage expansion.

Docked with X5ii

Docked with X3ii

The docking convenience of FiiO DAPs is great, but K5 is not limited to only that and can be paired up with other DAPs. Using a common RCA to 3.5mm cable you can feed Line Out of any DAP into Line In of K5. I went straight to the top using PAW Gold as my guinea pig for this test, as well as AudioQuest Evergreen RCA to 3.5mm cable, and ended up with a big surprise. Using Beyer's T5p 2nd gen, I found PAW Gold HO to sound nearly identical to PAW Gold LO + K5. Sure, there could be a few subtle differences, but overall it sounded very close where K5 combo even had a slightly wider soundstage.

Last but not least, I put to the test my ThinkPad T430s driving USB In through DACs of the docked X3ii and X7 while monitoring through T5p 2nd gen. This was really a proof of concept just to verify that both of the DAPs will be recognized by my laptop while docked, function as expected in USB DAC mode, and able to play FLAC files from Foobar2k on my computer. Everything worked flawlessly, with a loud and clear sound improvement. Pretty much anything would be a sound improvement over my laptop's HO from integrated motherboard sound chip. But it also fared very well against a number of my other USB DACs, especially in conjunction with X7 DAC where sound became more dynamic, more detailed, and with a consistent improvement in soundstage width.

Conclusion.

For sure you can call K5 a docking "jack of all trades" and "master of expanded dynamic sound". This latest FiiO docking amp is quite versatile in boosting the performance of portable FiiO DAPs as well as any other DAP, and you can also use it connected to a computer/laptop as USB DAC powerhouse. But among all of this it really shines with X7, replacing its IEM amp module with a more powerful alternative to take full advantage of ES9018S DAC performance. In my opinion, K5 bridges the gap between X7 portable and desktop use where on the go you can enjoy your IEMs and efficient headphones, while at home you can supercharge X7 not only by "charging" it up when docked but also by giving it an extra jolt of output power.