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Tone2 Pro - Spec Update, S/PDIF Out & More!

Our fourth installment of T2P news!

Updated Specifications

Tone2 Pro will be shipping out to you in January 2021 (early bird devices from HiFiGo will be shipping out in the next few days), which is just a month away! However before that our team is fervently evaluating every detail of the Tone2 Pro to ensure that it best meets the needs of our Tone Community. We’ve made the following adjustments:

  • Headphone output impedance is now better suited for lower impedance headphones.

  • PCM bit-rate has been pushed to the maximum of 768KHz 32bit.

These are the latest THD+N specs based upon the average measured value of 100 devices:

Input - Auto Mode:

Thanks to a suggestion from our forum user Mike, the default firmware installed in your Tone2 Pro will automatically switch input modes when it detects a song playing. By default, the input is set to “Auto”, and you can still manually select the input mode using the volume knob.

Input Priority: I2S > USB > S/PDIF

When the input is set to “Auto” and a song is playing on Bluetooth (I2S), the Tone2 Pro will automatically switch from S/PDIF or USB to I2S input. Once your song on I2S stops playing, Tone2 Pro will switch back to either USB or S/PDIF.

Software Volume:

Our original plan was to have the pre-installed firmware include XMOS software volume support, but some users could be confused by both Software Volume and Hardware Analog Volume. Therefore the pre-installed firmware only supports Hardware Analog Volume.

Special “Dual Volume” firmware (XMOS Software and Hardware Analog) will be released separately at for the users who wish to use both volume controls in their Tone2 Pro.


Tone2 Pro will support S/PDIF Out when loaded with a special version of our firmware.

The Balanced RCA connector(J4) carries both SPDIF_OUT and SPDIF_IN signals via it’s PIN3 and PIN1.
  • Turn your Tone2 Pro into a USB to S/PDIF Converter

  • Direct digital-signal from USB to S/PDIF Out

  • Sample Rate: S/PDIF Coaxial Out can support up to 192KHz 24bit

With regards to firmware support, the pre-installed firmware does not support S/PDIF Coaxial Out; MQA decoding requires too many XU216 processor cores and the “S/PDIF Out” firmware will not be able to support MQA decoding. As with the “Dual Volume” firmware, the “S/PDIF Out” firmware will be released separately on our file server at for interested users.

You will require a “Balanced RCA to Single-End RCA Adapter” to use S/PDIF Out, as Tone2 Pro uses the standard (single-end) RCA cable for S/PDIF Coaxial Input.

Wishing You a Marvelous 2021:

Once again, thank you everyone for your love and support during the challenging year of 2020. Khadas Team looks forward to a brighter 2021, and we hope that Tone2 Pro will bring many of you listening pleasure!

For those of you who haven’t yet used your $30-off Tone2 Pro coupon, please be reminded that the coupon will expire in 2 days on the 31st of December 2020. Go to Khadas Shop to pre-order Tone2 Pro at $30-off:


Khadas Team

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