Volume control for preamp out

Reading FAQ i see it is possible to have volume control on it. Im desperate to have some kind of volume control for speakers cause i cant afford or cant find something that fits my needs at the moment. Im getting JBL lsr305, which are active, thats why the desperate need of a preamp.

Any chance for a separate firmware release with hardware volume control enabled?

Aside of the preamp out volume control i mentioned, i was already expecting windows to be able to control the tone2 hardware volume (as usual with most dacs?). So it would be perfect for me, because i planned to use it temporary before getting a competent passive knob.
Personally i was confused with the lack of this ability and cant see how it could be that much complex to have it, as far as i know most dacs work that way.

I understand tone2 may be a little different having the separate volume control chip for headphones while being able to output in all outputs at the same time but i really dont think its necessarily a bad thing or confusing at all.

bonus question: would it be possible to have an option on the encoder to switch the knob’s volume control between HP analog and DAC’s digital?
If that was possible it would be aboslute perfection, not much need for a passive knob, at least for me im a digital volume believer. I cant afford 400$ stepped knobs xd.


I use a nobsound passive balanced preamp between my tone 2 pro and jbl lsr30x. Can be found on Amazon for under 40 usd. Works great and has a good pot.

Something like this should work:

Or you could get an adapter so that you can connect the JBLs via the 4.4mm Pentaconn headphone output on the Tone2 Pro. For example:

1 im not looking for those kind of preamps

2 i already have hd660s connected with pentaconn

easiest and best solution for now would be enabling hardware volume control, for me at least.

From what I understand, this is not as simple as a firmware update. Changes to hardware would be required to implement proper hardware volume control over the RCA outputs. Perhaps @Gouwa or someone else here can confirm.

If you require a DAC with digital preamp functionality, the Khadas Tone2 Pro is not a great choice, but I feel that Khadas was transparent about this in product information. There are plenty of other DACs in this price range that offer this functionality. It sounds like you just bought the wrong DAC for your particular use case.

Actually nope, and we will release new firmware to support Pre-Amp application.

Let’s take a look on the diagram block of Tone2 Pro below:

There are three volumes maximum for T2P:

  • Hardware/Analog Volume: for headphone jack only
    • Adjusting the NJU72315 chipset via I2C
  • Software Volume: for both RCA and headphone jacks
    • Adjusting the volume control registers of ES9038Q2M DAC chipset
  • USB Digital Volume: for both RCA and headphone jacks
    • Adjusting XMOS

The pre-installed firmware for T2P with Hardware volume enabled only and with fixed RCA line out. And we plan to enable the DAC software volume for preamp applications in the future:

Let’s say the new firmware with dual volume suppport and the Pre-Amp mode also setup via the GAIN mode:

  • In Gain mode, usually for LOW and HIGH gain modes only
  • To enable the Pre-Amp mode, you will need:
    • Toggle the knob to HIGH gain mode first
    • Toggle a lot to enable the Pre-Amp mode
    • Before changing to Pre-Amp mode, the system will do:
      • Lower down the DAC volume to certain value first (in case the headphones still there)
      • Maximum the hardware analog volume
    • The VOLUME RING LED will be different colors for hardware volume and DAC software volume

Any feedback are appreciated :slight_smile:


Not a fan of having to mess with the gain to toggle with that setting. Much less having to actually change the gain. Not much of a problem but sounds a little confusing to me and unnecesary.

Ideally i think it would be better to add an extra menu where you switch between software volume on and off.

With software volume enabled the volume knob would still be usable for either of the functions (software volume/headphone amp)? If yes im not sure which one i prefer to have it.
I think for headphone amp because i use it to mute headphones when using speakers. But, if there was a way to mute headphone out, then i would much prefer having the knob for software volume.

Maybe im just making things up and enabling software volume doesnt change how the knob works, sorry if thats the case.

thanks again

I would think this would be one one of the most sought after features for the Tone2 outside being able to use the 3.5mm and 4.4mm jacks as pre-amp outputs. Is there an ETA on this being implemented on the next firmware release?
Personally I think it would be simpler to just be able to switch between a pre-amp and amp mode, where as in pre-amp mode all outputs (RCA/3.5mm/4.4mm) act as pre-amp outputs controlled by the volume control.

Will get back to you a ETA this week.

Actualy, we’ve completed the development & release a bata firmware for Dual Volume, but our engineer team found that if we are able to merge the two firmware “normal firmware” and “dual volume firmware”, will be better user experience.

Thanks for folllowing up.


Hi forks,
We will release the new firmware V1.3 in early August.

Good day!


Thanks. Can’t wait to share my test results once it’s out. :slight_smile:


Great, will be ready to test it

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Hows it going? Seems like its gonna be a big update

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Hi @Gouwa

any news on the new 1.3 firmware ?

Howdy Folks!

Sorry for the delay due to more time for testing, please forward to:

Have fun!

Thanks, will test it today!

The GAIN CPNTROL is working properly and it’s a nice new feature.

Did you replug the power?

And please show the screenshot below to me:

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Everything’s OK on my side :

  • unzip the firmware
  • open DFU Tool and select the firmware
  • update
  • windows drivers are reinstalling and need a computer reboot
  • reboot and everything’s OK

I’ll give this a try this evening and post before/after test results. If they look good, I may have to buy another one. :wink:

Edit: In stalled v1.3. No issues. Working great. I won’t get around to remeasuring tonight, but I am doing a bit of listening, and it sounds terrific. I don’t expect the measurements to show anything different. The preamp volume control works as expected. No noise. No drama.

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