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Khadas Tone 2 Pro Review – The Duality of DAC

Pros –

Gorgeous build and svelte design, Extremely small footprint, Rotary encoder feels great, Linear and refined sound, Multi-dimensional imaging in DAC mode, Linear power supply input, Integrated amp offers a low OI with black noise floor

Cons –

Control Scheme could be streamlined, BT module and balanced RCA cables add to cost, Driving power is just sufficient for headphones

Verdict –

Even at its elevated price tag, the Tone 2 Pro remains an excellent DAC paired with a simply good integrated amplifier that does well for IEMs and suffices for headphones.


Introduction –

Khadas’ parent company was founded in 2014 where they focused on OEM product design. Khadas represents their consumer brand with in-house developed products directly under their branding. The tone board was their first USB-powered DAC, a compact and streamlined design implementing ESS’ ES9038Q2M chipset that was lauded for its implementation and superlative measurable performance. More so, the Tone board was one of the cheapest high-performance options on the market making is a very popular choice with enthusiasts on a budget. The Tone 2 Pro then represents a huge reinvention of the Khadas name; demonstrating their serious intention to uphold a legacy of performance for cost whilst addressing former complaints with build and versatility. The Tone 2 Pro features a substantially more premium design, integrated amplifier, balanced connectivity and updated USB decoder. So not only does it represent a jump forward in DAC performance and codec support, it now features an amplifier for greater versatility on top.

The Tone 2 Pro surely feels like a far more complete offering than its predecessor and with that comes an increased $199 USD asking price. You can read more about it on Khadas’ website here and treat yourself to a unit on HiFiGO.

Contents –

Behind the Design –

Updated Audio Architecture

Much like the original, the Tone 2 Pro implements the ESS9038Q2M DAC chip paired with a more robust USB decoder and 3 stage integrated amplifier with four OPA1612 OPAMPs – with the two headphone outputs having separate amplifier circuits. An Intel Altera CPLD also enables jitter filtering and pre-shaping. The revised PCB design and hardware permits a notable jump in measurable performance over even the original Khadas Tone Board.

Updated IO

In order to maintain a compact design in addition to balanced connectivity, Khadas have designed balanced RCA connectors with 3-pins each. You will need to purchase Khadas’ proprietary cables through their website since this standard is not common at present. Due to the metal design, the company was unable to integrate Bluetooth connectivity. However, a separate module is available that connects to the second Type-C input port.

Wide Codec Support

Using the latest CMOS XU216 USB chip, the Tone 2 Pro support full MQA decoding. Khadas have implemented a thermal pad that dissipates heat through the device’s metal shell to keep the chip cool. This ensures bit-perfect audio transmission and reduces thermal noise. With the Bluetooth module, the Tone 2 Pro will support Qualcomm’s aptX and aptX HD in addition to LDAC, the highest quality wireless codecs available.

Unboxing –

The Tone 2 Pro comes in a small rubberized hard box that provides a premium first impression. Inside is the DAC/AMP itself. Beneath is the USB-C cable in addition to manual and warranty papers. This is quite typical for most source devices though I do wish it came with a braided cable as the original Tone Board did, the new cable is quite stiff and rubbery. That said, it now assumes Type-C to Type-C connectors which means it can be used as an OTG cable aligning with the Tone 2 Pro’s MFi certification.

Design –

The original Tone Board was lauded for its cost-effective performance, yet this came at the expense of a proper housing. Buying aftermarket, at least in Australia, added immensely to the cost which undermined its value proposition. The Tone 2 Pro is an immediate evolution in this regard and a stunning package through and through whilst remaining low-key enough to slot neatly into a wide range of setups. It remains very compact and assumes a razor thin profile with angulated panels reminiscent of performance vehicular design, especially in red as pictured here. The aluminium shell feels incredibly solid and the finish impresses too, with an even sand-blasted exterior and smooth edges. The base is rubber which keeps it well-planted and prevents scratches. Special focus was placed on the rotary encoder which serves as the main control scheme.

It too has a metal and rubber construction that feels great in the hand. Though it is a digital pot, Khadas have devised a gasket sealed system with viscous damping gel that provides a smooth and weighted action, imitating a high-quality physical pot with great success. Besides this, users will also note the inclusion of two Type-C inputs, enabling the device to be powered by a 5V linear power supply with the other handling data input. Khadas note that the device prioritises power through this port, though the device is perfectly useable running from a single input too. On the right are the 3.5mm and 4.4mm amplified outputs while the rear houses a Coax input in addition to balanced RCA plugs. Of note, regular RCA works just fine for single-ended use. Altogether, I’m a huge fan of the design, it feels incredibly dense and well-constructed.

Usability –

Setup is simple as with any other source device, simply plug in a type-C cable and the device powers on. The user can then connect to the DAC using an RCA cable or take advantage of the inbuilt amplifier using its headphone outputs. As aforementioned, the second type-C input is for power alone similar to the Earmen devices. Connecting a linear 5v power supply to the i2s labelled port can potentially provide lower noise if the current USB power source is not ideal. For the purpose of evaluation, I am using an external power source here.

Controls

The Tone 2 Pro does make some concessions in its pursuit of a streamlined aesthetic design – that being its limited control scheme. The user is only able to interface with the device using the rotary encoder which rotates and also clicks downwards. Through this, Khadas have managed to implement a fairly versatile system which works in tandem with an RGD LED indicator that shines from beneath the knob to denote the current setting menu/mode. In addition, the light illuminates to surround more of the circumference as the volume is increased.

So, the user is able to toggle through various menus by double pressing the button which will permit rotation to control other functions such as track skip, filter, gain and input in addition to basic volume adjustment. I personally would have preferred a spring-loaded encoder that may have lacked the same smooth action but would have provided better feedback for navigating settings. Similarly, an app or desktop program to control the device with a GUI would greatly simplify the process. It is far easier to understand this system by watching Khadas’ own video that you can view here.

Next Page: Sound Breakdown & Verdict

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