Review: Questyle CMA18 Portable

Design and specs

Current mode amplification is far from the only selling point of the CMA 18 Portable. Probably the first thing you’ll notice is the design which, for a portable device smaller than a deck of cards, is drop dead gorgeous. 

Set inside a sandblasted aviation-grade black anodised aluminium frame with silver-polished control buttons, the most distinctive feature of the CMA18 Portable has to be its crystal-clear Corning glass surfaces. While glass is not always optimal for a portable device – especially glass this smooth and potentially slippery – it gives the device a high-gloss premium finish that’s surprisingly fingerprint and scratch-resistant.

CMA18 Portable is, at first sight, far smaller than I expected, measuring only 11 x 7 x 1.5cm, shorter but thicker than your average smartphone. It feels firm in hand, weighing less than 200g, but is also denser than it looks. As mentioned above, the glass is slippery, so best to hold it on the flat metal sides to avoid unwanted accidents. Better yet, I can strongly recommend the leather case, which you can buy directly from Questyle for the currently-reduced price of $49. 

The design kicker, though, is the transparent glass cover on the front, which doubles as a window to the neat-looking electronics of the primary PCB below. This isn’t the first time I’ve seen Questyle’s take on a transparent cover; the company original flagship desktop DAC/amp, CMA800i, offered a fully-transparent glass cover as an option, and the more recent M15 dongle sports one too. 

Add to this the illuminated LED lights used to display the various function and charging modes on the PCB, and you have a device that almost feels ‘alive’ when in use. Sad as it probably sounds, I get excited just reaching for the volume buttons on the CMA18 Portable, knowing that I’m about to enjoy a little light show in the process. 

Speaking of buttons, there are four in total, all on the left-hand side of the device: power on/off, volume up, volume down, and function. While I generally prefer buttons to wheels for volume changes, I do wish there were more steps to CMA18 Portable’s volume control. With more sensitive IEMs you may just find yourself wanting a touch more or less volume than a single step will give you, even in standard gain.

The function button (below the volume buttons) is used to change input modes (balanced, line-in, AUX-in, USB, optical and Bluetooth), and also to set various operating modes, like charging during playback. This latter function was added to the CMA18 Portable with the first (and so far only) firmware update, allowing you to charge the player from a connected source or charging plug while playing music. 

Unfortunately, there’s no battery bypass mode, which means you have approximately 10 hours of battery life on a full charge, or continuous playback via the battery while it’s charged externally. This does mean the built-in 4500mAh batter is likely to degrade over time, but given how conservative the power requirements are, it should still give you many years of service before a replacement is necessary. 

There are also two switches just below the buttons: gain and hold. Two gain settings are available, high and standard, and unless your IEMs and headphones are especially insensitive, it’s safe to leave the default standard gain engaged. The hold switch is useful for preventing accidental button presses during use, but it will be interesting to see if it gains any additional functionality with future firmware updates. 

DAC duties are handled by a single AK4493 chip and the latest XMOS XU316 platform, capable of decoding 768 KHz PCM and native DSD512 streams, with automatic switching between both. This is a change for Questyle, given its traditional use of ESS Sabre DACs, and I can only assume it was selected for the particular tuning profile and power requirements the designers were targeting. Regardless, it’s a welcome change, given AKM’s more organic-leaning tonality. 

For a palm-sized device, CMA18 Portable has a generous array of input and output options. It features both 4.4mm balanced and 3.5mm single-ended analogue ports, the latter doubling as a digital optical port as well. It also has corresponding 4.4mm and 3.5mm headphone output ports, along with a bi-directional USB-C port. 

The combination of these ports is also quite interesting; for example, there’s no discrete line-in, despite the analogue inputs, with all signals routed through the DAC section before being output to the headphone ports. This means you can’t use the CMA18 Portable as a standalone amp for a DAC or DAP, even though it will accept an input signal and you will be able to bypass your device’s amp section. 

On the flipside, CMA18 Portable offers the rather unique ability to record the incoming analogue signal and output the resulting audio stream through USB. In this way you can use the device to record the output from your vinyl player, for example, or from your mastering deck, and convert it into a usable sound file on a smartphone or desktop computer. This is a feature that Questyle desktop DAC/amps have offered for a while, so it makes sense that the ‘crossover’ CMA18 Portable has it too.   

Last but not least, CMA18 Portable also features Bluetooth input as an option, with support for all modern formats including SBC, AAC, AptX, AptX HD and LDAC. I tested this function as part of this review, as you’ll read in the sound impressions below. 

Continue to sound impressions…

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ABOUT AUTHOR

Picture of Guy Lerner

Guy Lerner

An avid photographer and writer 'in real life', Guy's passion for music and technology created the perfect storm for his love of portable audio. When he's not playing with the latest and greatest head-fi gear, he prefers to spend time away from the hobby with his two (almost) grown kids and wife in the breathtaking city of Cape Town, and traveling around his native South Africa.

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