REVIEW

mid/high) and output selectors (DAC/PRE/Headphones). Other controls include input selector and standby. Above this are LEDs to indicate the input source (USB/Opt/Coax/line/BT). In the middle is a large volume control with a colour-changing RGB backlight surround to indicate sampling rates and Bluetooth codecs.

At the rear of the unit are the inputs including coaxial, optical, USB, and a Bluetooth digital aerial socket plus RCA and balanced 4.4mm analogue inputs, plus RCA and XLR analogue outputs should you want to connect to an amplifier or your powered speakers. On the side is a USB C port to connect to your mobile device for more control via an app.

The phone app controls Bluetooth codecs, DAC filters etc. K9’s amplifiers are the excellent THX AAA-788+ chips that can give exceptionally low distortion and excellent detail and dynamics when using both low and high-impedance headphones. Indeed, the amp works well with headphones/IEMs from 16 to 600ohm. The PCB is a partitioned layout meaning that the power supply and signals are separated, including analogue and digital stages. The balanced audio circuitry is equally complex with 6 stages from input to output. A dual-mode clock management design is deployed with a femtosecond clock for USB/Bluetooth and PLL clocks for optical and coaxial decoding. Typical of products at this price point, USB operates up to 384kHz-32bit/ DSD256, coaxial up to 192kHz-24bit, and optical 96KHz-24bit. The unit also supports MQA tracks which given the recent news is moot. A Qualcomm QCC5124 looks after the Bluetooth ensuring it is low latency for gamers and high bit rate for audiophiles. Finally, the Fiio uses an internal linear power supply with four massive 4700uF capacitors.

The presentation box itself is crammed with goodies including a power cable, 3.5mm adaptor, BT aerial, spare fuse and the custom stand so that you can sit the PRO on its side, should you wish to save space. At 200 x 220 x 72mm, this is a very compact but well-laid-out unit. The presentation is very good including a basic but good sized instruction manual.

Sound Quality

Getting it out of the box, the only clue to it being the ESS version was the gold rim of the volume control and gold “PRO” badge. The word “ESS” appears on the base, as does a 110v and 230v switch, which I carefully checked before turning on. For most of the listening, I used Coax and BT. Initially, I set up the Fiio X5 digital output, which actually performed surprisingly well. Other than that, I used the excellent SE180 DAP from Astell and Kern, itself also affording an ESS ES9038PRO DAC, and I listened with Sennheiser, Audio Technica, Meze, and Campfire Audio headphones/IEMs. Turning on the unit is via a toggle switch at the back plus the standby button at the front right. Instead of pressing the latter, you can also turn the volume control to wake it all up. Nice idea. The RGB edge then changes colours until it tunes into whatever the input is. For example; “white” is LDAC, and “Green” is DSD.

The first of the digits were Johnny Cash’s “The Man Comes Around” (24bit/96kHz). With excellent detail and an impressive spread of instruments, Johnny’s voice was hypnotic as he spoke and sang. There are three levels of gain on the K9 front panel (indeed, all the switches are rather small but keeps the front panel looking minimalist), and for most of the time I used the “high” setting and my Sennheiser HD650’s needed to be at ½ way on the dial to get a serious level of sound. Indeed, for Dave Brubeck’s ‘Blue Rondo’ I needed to turn it up to 2 o’clock. The amp, however, should be ok with all but the most inefficient planar headphones.

Julia Fordham’s “Porcelain” is a very laid-back album with great sounding vocals and instruments. The cymbals were very tight and Julia’s distinctive voice – especially the low notes – was very honest sounding. The Fiio gave a very good performance, if a little gentler than I remember. This was very musical but a tad too tidy and cleaner than I expected. I wanted a little more oomph and musicality to get me really engrossed, but this was soon to be experienced with Kitaro’s ‘Live in America’, another very laid-back album with lots of interesting sounds such as thunder, synthesizers, and audience applause in this live performance, giving it an air of ambiance and enchantment. That bass thunder was superbly tight and clear as were the strings, synths, and woodwind. I just felt the bass was a little quieter than I would like, even when using the bass-brilliant Meze 99 headphones. The top end from the synthesizers and audience claps were very clear and the exceptionally quiet running THX AAA-788+ made this a joy to experience, even at loud listening levels. Certainly, the mids and higher frequencies are clearer,