Wesion (Shenzhen Wesion Technology Co. Ltd.) founded in 2014 in Shenzen, China, is the company that owns the brand Khadas. In addition to OEM and ODM solutions, Wesion develops, manufactures and markets Amlogic and Rockchip single board computers (SBCs) for the open source community and streaming media player industry. Using its own software and hardware development capabilities, the company achieved what few industrial company's from China have managed: to build a brand and a strong user community out of the Khadas business.
After months of consultation, tons of feedback from the market, and a lot of teasing online communities, Khadas is now accepting orders for the Tone2 Pro - the second generation Tone Board following the Tone1. For this project, Khadas paired an ESS ES9038Q2M DAC with four TI OPA1612 operational amplifiers, and three buffer amplifiers.
This 3-stage amplification pathway enables Tone2 Pro to drive a wide-range of demanding audiophile-grade headphones with impedances of up to 150 ohms. As Khadas explains, "the OPA1612 was selected because it provides superior audio quality and excellent distortion characteristics; THD + noise is below 0.00008% throughout the audio range (20Hz to 20kHz)."
Other additions to the Tone2 Pro include a 4.4mm balanced headphone jack in addition to the standard 3.5mm single-end jack. The Tone2 Pro's aluminum enclosure incorporates a hybrid digital/analog volume control knob, allowing users to rely entirely on analog signal attenuation for improved sound reproduction.
And with not one, but two USB-C ports, the Khadas Tone2 Pro allows users to connect a 5V linear power supply to the second USB-C port whilst having USB-C data on the first for excellent power-noise isolation. When powered by a compatible 5V linear power supply users can connect via Tone 2's secondary USB-C port (I2S) and the supply will take higher priority over USB power.
And interestingly, the Khadas designers added an industry-first balanced RCA line-out - a novel design that uses three signal-pins (for an inverse analog signal) instead of two, yet retains the same size and form factor as regular RCA connectors. The Tone2 Pro actually uses custom designed slim-profile RCA jacks that are ideal for portable applications and these balanced RCAs retain backward-compatibility with standard RCA connectors (single-end mode). The company also confirmed they intend to sell a balanced RCA to XLR-3 converter cable (see more info here: khadas.com/balanced-rca)
The Tone2 Pro board supports up to 32-bit/384kHz PCM digital audio and bit-perfect DSD512, with the ESS ES9038Q2M DAC providing an analog line-out signal with -118dB THD+N. With the addition to support MQA file decoding, thanks to an onboard XMOS XU216 processor, the Tone2 Pro delivers hardware-native, USB class II, asynchronous "unfolding" of MQA data at reasonable file sizes for web streaming bandwidth requirements, and also for local high fidelity audio playback.
And the Khadas Tone2 Pro even doubles-up in functionality, with the users being able to leverage the two USB-C ports, using one for the mentioned 5V linear power supply or an add-on Bluetooth module - allowing users to buy a standard Bluetooth 5 module today (pictured below, the modules uses a Qualcomm QCC5125 SoC with aptX HD and LDAC support), and later order a new one with Bluetooth 5.2 with LE Audio and LC3 support when available. The other USB-C port can be used simultaneously for a PC / Smartphone / Tablet connection (data + power).
As Khadas highlights, "What sets apart our Tone2 Pro from other DAC products, is a slim-compact aluminum design, volume encoder, and balanced RCA ports; these are custom-designed RCA ports that squeeze balanced audio into a very slim profile (50% smaller than XLR-3); allowing the Tone2 Pro to be a portable Hi-Fi DAC that you can drop into your bag and go everywhere with."
The Khadas Tone2 Pro is indeed surprisingly small (the size of a pack of cards) and is extremely practical to use with its hybrid digital-analog control knob for headphone volume, RGB LED ring for status indication and feedback, which doubles as a rotary-push encoder for mode selection.
audioXpress is planning to feature a review of the Khadas Tone2 Pro in the magazine. For orders and updates check the Khadas website.
www.khadas.com/tone2pro
