Will the sound quality be better than the Tone 1. I found the Tone1 lacked body, though the audio is very clean.

We will ensure that the performance of Tone2 Pro is higher than the Tone1. After formal tests are conducted with specialized equipment and test benches, we tend to leave this question to the reviewers who will review Tone2 Pro in the coming days. Qualitative sound-quality is highly subjective, with some people preferring a clean and flat output, whilst others prefer a warmer bass and a punchy high-range with more depth and space.

Did you fix the "ESS hump" issue in the Tone2 Pro?

Yes this issue has been resolved in our Tone2 Pro.

Why do I hear a slight pop-noise from the balanced 4.4mm pentaconn jack when powering on the Tone2 Pro, whilst the 3.5mm jack remains silent?

The single-end 3.5mm jack is designed with a depop chipset to cancel the pop noise, and has a max of 2.3Vrms output. The balanced 4.4mm jack is designed to drive higher impedance headphones, and has a higher output at 5.0Vrms or greater; the depop chipset will draw down this performance and does not support higher outputs.

Is there a way of displaying the format and bit-rate when connected over S/PDIF?

Tone2 Pro cannot view the format and bit-rate of audio streams via S/PDIF. The S/PDIF-IN signal is directly fed into the ESS ES9038Q2M DAC, and bypasses the XMOS XU216 processor.


Coax is input or output?

Coaxial input. Originally we designed Tone2 Pro to support both Coax IN and OUT via the balanced RCA jack. You can use a standard RCA cable for Coax IN, and a balanced RCA cable for Coax OUT. But Tone2 Pro is likely to only support the Coax IN feature when it ships with the pre-installed firmware. The XMOS XU216 processer is already maxed-out to achieve all features such as MQA, SPDIF OUT and PCM768. We may release special firmware to support Coaxial OUT for users who want to use the Tone2 Pro as a USB to SPDIF adapter, just note that a special cable(balanced RCA to single-end) is required to support the SPDIF Coaxial OUT.

What is the voltage level of the RCA balanced connection, is it the standard 4V?

Yep, 4.0Vrms for balanced RCA mode, and 2.0Vrms for standard RCA mode (single-end).

What’s the spec-difference between Tone2 and Tone2 Pro?

Tone2 = Tone2 Pro - Headphone Amp - MQA. The Tone2 Pro is based on the XMOS XU216, whilst Tone2 is based on the XU208 (which is also used on Tone1). The Tone2 will have balanced RCA connectors, just like the Tone2 Pro.

Does Tone2 Pro support Bluetooth high-resolution input?

Yes the Tone2 Pro supports external bluetooth modules via the secondary USB-C port labelled I2S. Note that the pin-layout of the USB port is non-standard. Users can select the input source using the volume knob (rotary-push encoder). Input sources: USB Data, Bluetooth (via USB-C I2S port), and Coaxial S/PDIF IN

Does the Tone2 Pro support audiophile headphones?

Yes, we built-in a buffer stage amplifier to drive the headphones directly. They are connected with the hardware volume control, and each headphone has an independent amplification pathway. Headphone volume is independent from line-out.

Does the volume knob also control the output of the RCAs?

Our official firmware will only control the headphone volume of the headphone jacks, line-out will have a fixed output volume. It’s still possible for volume knob to control the output of line-out via adjusting the volume register of the ES9038Q2M DAC. In that case, there will be two types of volumes:

  1. DAC volume (digital) for both line-out and headphone jacks
  2. Hardware volume (analog) for headphone jacks only
But we believe two volume controls will be too complex for most users, so we just fix the DAC's digital volume at maximum (highest performance), and only apply hardware volume control for the headphone jacks. We may release dedicated firmware to enable control of the DAC's digital volume for the line-out, if this is required by specific users in the future.

The I2S USB-C port supports 5v linear power supplies up to how many amps exactly? is it 0.9A, 2A or 3A?

The Tone2 Pro consumes a maximum of 0.62A at 5V (3.1W) whilst playing PCM 768KHz 32bit music, so any linear power supply in excess of 5W will work just fine.

Are Tone2 and Tone2 Pro similar or different?

Nope, the Tone2 is a different product from the Tone2 Pro: Tone2: DAC only and will be sold as a bare board Tone2 Pro: DAC + HPA, with MQA support. Will only sell as a finished product.

I was wondering what "filter mode" means in the Tone2 Pro RGB ring-light indicator?

LINEAR FAST: Linear-phase fast roll-off filter
LINEAR SLOW: Linear-phase slow roll-off filter
MINI FAST: Minimum-phase fast roll-off filter
MINI SLOW: Minimum phase slow roll-off filter
APODIZING: Apodizing fast roll-off filter
HYBRID FAST: Hybrid fast roll-off filter
BRICK WALL: Brick-wall filter

Check the document below from ESS official website for further information:

How many levels of volume does the Tone2 Pro have?

The Tone2 Pro's amplifier has a range of 0 to 64dB, and it's firmware supports 32 levels, each level is 2dB; this is controlled via hardware analog volume.

What are the performance impacts of using a Linear Power Supply, PC USB Power Supply, or Mobile Phone Switching Power Supply?

There is no impact on performance when using an LPS and PC USB power supply to feed your Tone2 Pro. You may notice a background-hum when using Mobile Phone Switching Power Supplies, so this is not recommended.

How many clocks can I connect to the I2S interface?

The I2S interface does not need an external MCLK; it is governed entirely with internal clocks.There are three internal clocks at 45.1584m, 49.1520m and 100m. The crystal oscillator of the last USB input source is reserved.


What about balanced RCA to XLR-3 cables?

We will produce an adapter or cable for existing products with XLR-3 connectors:

  • Balanced RCA to XLR-3 male adapter (0.2m)
  • Balanced RCA to XLR-3 male cable (1.0m)
You may purchase them at Khadas Shop. We will also launch a balanced RCA cable when compatible products like Pre-Amp/Amp/Headphone Amps are available in the market.

What connection cables will you be providing in the package?

The Tone2 Pro packaging is designed to be small to save on space and materials, so only a 1m length USB-C to C cable is provided inside the box. Those who require extra cables and converters can purchase them separately from Khadas Shop.

The Tone2 Pro has headphone jacks for headphone listening?

Yes, we built-in a buffer stage amplifier to drive headphones directly. They are connected with the hardware volume control (volumee knob), and each headphone jack (3.5mm / 4.4mm Pentaconn) has an independent amplification pathway. Headphone volume is independent from RCA line-out.


Is there a version of the Tone2 Pro for the VIM3 also?

We will release the “Tone2”, which is a bare board version for VIM SBCs. Tone2 Pro will only be sold as a finished product due to the MQA license restrictions.

There is a Generic version and VIM version? Or is there just one version?

Tone2 Pro is a finished product, that has an MQA license and will be sold with an aluminum case. Tone2 will be a bare board suitable for docking with VIM SBCs.

Can the USB-C input be used with the USB-C output of my phone?

Yes, Tone2 Pro can be powered by most Android smartphones over USB-C. iPhone users will need an external 5V power bank connected to the secondary USB-C port labelled I2S, as the iPhone has insufficient power to drive the Tone2 Pro.

Is this an AMP + DAC combo?

Yes the Tone2 Pro is a DAC + Headphone AMP.

Is the USB-C port version 3.0 or 3.1?

Tone2 Pro is equipped with USB 2.0; both USB 3.0 and 3.1 are compatible with USB 2.0.

How do I connect the HDMI/I2S output from my digital sound card to the I2S input on the Tone2 Pro?

Tone2 Pro only supports I2S via the USB-C port. If your sound card has HDMI-I2S output, you will need to customize a home-made cable to transfer the audio from a HDMI connector to a USB-C (male) connector.

Can the Tone2 Pro be used as a VIM3 or Raspberry Pi hat?

Tone2 will follow the Tone2 Pro form factor and support bottom-to-bottom mounting for VIM3/3L SBCs. Visit Khadas Forum for futher information: "Tone2 Pro: Pre-Orders Begin 16th December @ $169.90! - #116 by wanthalf - Announcements - Khadas Community"

Does the Tone2 Pro have ASIO driver support?

Yes, to enable ASIO support you have to install the Khadas Tone Driver V4.8x, download it from this link:

I am using Windows 10, do I need to download a driver for 32-bit 384kHz?

Yes you should download our Tone2 Pro driver from

I wasn’t able to find a Linear 5V USB power supply for the I2S input. Will a normal usb-c adapter work? Does the 4.4mm pentaconn jack use standard wiring?

Yes, a normal USB-C adapter can work and the 4.4m JACK is wired per standard specifications. Tone2 Pro has 7 connectors: * USB Port: it can connect to a PC/phone/tablet PC and so on.
* I2S Port: it can supply audio from our Bluetooth module, or 5V power input from a linear power supply.
* Orange balanced RCA: it can be used for coaxial input and coaxial output.
* White balanced RCA: the left balanced signal or left unbalanced signal output.
* Red balanced RCA: the right balanced signal or right unbalanced signal output.
* 4.4mm headphone Jack: connect to your 4.4mm headphone.
* 3.5mm headphone Jack: connect to your 3.5mm headphone.

Could the Tone2 Pro power 600ohm headphones or would a separate amplifier be necessary? I’m assuming a balanced connection would be necessary for this?

The Tone2 Pro is designed to drive low impedance headphones with a maximum of: * 150ohm for the 3.5mm single-end jack
* 300ohm for 4.4mm balanced pentaconn jack
To drive 600ohm headphones, we will suggest that you connect an independent headphone amplifier to the RCA line-outs for more powerful and distortion-free sound.

Can the Tone2 Pro output to a tube amplifier?

Yes, Tone 2 Pro can be connected to any kind of amplifier via the balanced RCA line-outs. A tube amplifier is just another kind of power amplifier.

The audio outputs of my projector are 3.5mm. How can I connect my projector to Tone2 Pro such that it outputs audio to my amplifier?

There are three kinds of audio source inputs:
* USB 2.0 Input,“USB” marked
* Coaxial(SPDIF) Input, “Coax” marked
* Bluetooth Input,“I2S ”marked,which you need to buy a Bluetooth module to plug into. I think coaxial input may be the best option for your projector. In most cases, the projector will accept HDMI input from a PC, and you can connect your PC directly to your Tone2 Pro over USB.

Does the Tone2 Pro work with the USB output of a PlayStation 4?

Yes it works!


Will the Tone2 Pro be a development platform or an end-user product?

Tone2 Pro will sell as a finished product only. Khadas will launch the Tone2 (non-Pro) as a DIY Kit in the future, without MQA support.

Will Tone2 Pro be open source like Tone1?

You can be sure that Tone2 will be open source like the Tone1.

Will it completely unfold MQA for Spotify?

Yes, full MQA decoding for both the MQA Core and MQA Renderer.

Is Tone2 Pro still a USB DAC that perform the same function as the Tone 1?

Yes the Tone2 Pro is still a full-featured USB DAC, with the addition of a headphone amplifier.

If I connect Tone2 Pro to my PC, will I use the primary USB-C for signal and the secondary for power?

The primary USB-C supports both power and data from your PC, Laptop, Tablet or Smartphone. The secondary USB-C is for connecting 5V linear power supplies that will bypass the primary USB-C power.

I’m wondering if my Tone2 Pro could unfold full MQA if connected with budget a transport/music player like the Hiby R2?

The Tone2 Pro supports full MQA decoding. To support MQA, the music player also needs to support playback of MQA files and streams.

Is there a XMOS Audio Driver for the Tone2 Pro, and how does MQA activate on the unit?

You can download the Khadas USB Driver from this link: MQA can be used immediately and does not require activation.

Can the Tone2 pro be connected to an Android phone over USB-C (USB)?

Yes, the Tone2 Pro can be powered by most Android phones and iPad Pro devices directly via a USB-C (male-to-male) cable. If the phone or tablet cannot supply enough power, you can power the Tone2 Pro with a powerbank connected to the USB-C (I2S) port.

Why have S/PDIF and I2S inputs without MQA support?

The ESS ES9038Q2M DAC does not support MQA decoding. In the case of Tone2 Pro, the XMOS processor XU216 does the MQA decoding. The I2S input on the USB-C port, GPIO pins, and the SPDIF-IN are routed to the ESS DAC directly, and not through the XMOS processor; therefore these inputs do not have MQA decoding support.

Can I connect two audio systems simultaneously to Tone2 Pro (Coaxial + USB)?

Tone2 Pro supports both Coaxial and USB inputs, and you can set the preferred input manually or leave it in automatic mode. When set to AUTO, the coaxial input has higher priority over USB input.

In Mac OS X, it says: "The selected device has no output controls"

Tone2 Pro's default firmware only has hardware volume control. We will release dedicated firmware with dual volume support in the near future, you can upgrade your Tone2 Pro's firmware to enable software volume.

Can I use Tone2 Pro with the iPad 9.7 inch (2019), or iPhone? (Lightning Connector)

Yes you can use the Tone2 Pro with devices that do not have a USB-C port, however do note that the experience remains rather clunky. If you must, refer to this forum post for the converter cables you'll need to buy:


Do you ship globally?

Yes we do, just provide a valid shipping address and working handphone number for the courier.

When will it be launched?

Pre-orders will begin on 16th December.