The first version of the Khadas ToneBoard rocked the ultra compact HiFi DAC market thanks to its excellent audio performance & measurement. If this first success is mainly due to an integration work aimed at pushing each of the on-board components to the maximum of their capacities, it also left little space for its successors to stand out by their level of material optimization.

In this context, the Khadas TONE2 PRO naturally brings its procession of material improvements which are added to this irreproachable technological base, but it is especially at the level of its functionalities, its ease of implementation and its hyper-scalable architecture that the latter differs from its successor.

Once again, meet the famous digital to analog conversion circuit (DAC) based on 32-bit ESS ES9038Q2M chip with PCM support up to 768kHz and native DSD512. The latter is now accompanied by a buffer / headphone amplification stage in 4 x OPA1612 for driver of advanced headphones.

The XMOS U216 USB circuit incorporates a modified firmware natively supporting bit-perfect MQA flows on its asynchronous layer. A second USB-C connector completes the connection and allows completely new integration scenarios.

XMOS U216 & Native MQA Support

The Tone2Pro embeds an asynchronous XMOS U216 USB Audio chip (against U208 on the first generation). This component is part of the best generation of USB interfaces dedicated to high fidelity audio with its multicore architecture, its native DSD capabilities up to DSD512 and its processing of clock signals with surgical precision.

The integrated firmware is capable of natively decoding MQA streams (Full MQA Decoding & Redering). The Tone 2 Pro can therefore play your MQA files without resorting to software decoding and thus take advantage of this technology without compromising a single bit of resolution.

DAC ES9038Q2M

The Tone Board uses a combo of two ES9038Q2M decoder chip. It is not only ESS flagship, but also one of the best hardware solutions today for high-fidelity audio decoding. Each channel has it own conversion stage which greatly benefits the stereophonic image precision. 

The latter embeds the HYPERSTREAM 32 BIT architecture with native DSD support. It is complemented by advanced reconstruction filters and has excellent finesse in dithering.

This element is the heart of the device. It promotes precise audio reproduction with sustained dynamics and a wider soundstage. Offering excellent performances such as an SNR> 118dB, a very low Harmonic Distortion rate and a considerably low jitter.

Headphone amplifier x4 OPA1612

The ES9038Q2M DAC outputs to a headphone buffer / amplification stage operating from four OPA1612 operational amplifiers as well as three amplification buffers.

The stage was therefore built in such a way as to be able to easily drive difficult headphones with impedances that could reach 150Ohms. Besides its power and stability, the OPA1612 is above all an ideal solution for high fidelity audio applications, especially with a noise level below 0.00008% over the entire 20Hz-20kHz range.

Automatic input switch detection

The Tone2 Pro is equipped with a circuit capable of automatically detecting that one of its input is receiving an audio signal. This very comfortable function allows the card to adapt to your use of your audio environment. It is of course possible to block automatic switching mode and force manual selection in cases where your Tone2 is connected to several sources simultaneously.

If the automatic detection mode is activated, the DAC will activate the input receiving the signal by itself, respecting the following order of priority: I2S input, then USB input, then SPDIF input.

Khadas Tone2 Pro review by Audio Science Review (Amir)

" As a plain balanced DAC, the basic performance of the Tone2 Pro is superb "