Tone 2 pro crackle sound

Hi. I have an issue with My Khadas Tone 2 pro dac.
It sometimes crackles when I use high er streaming than 16bit/44.1khz.
Both usb and spdif input.
In the beginning it was only when it was cold, but know it can do it also when warmed up, but not all the time.
I have used 2 different streamers, I have recycled power, I have reinstallef drivers and firmware.
I use an external power supply, but I have tried to power it via streamer usb connection.
Do I have a defective Unit?

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How are you powering the DAC?

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Hi Tonny,
Can you take a phone to show the setup of your application? And as the @dsnyder0cnn mentioned, the power input setup info comes important.

Good day!

The power supply is an Ifi audio Ipower x, which can not be seen at the picture

Do you think the Ifi power supply is a problem?

Curious, those RCA connector’s wires appear to be just plain wire. I think shielded wires should always be used for this type(level) of signal transfer. Are they using shielded wires?

Yes they are plain unshielded slightly twisted Duelund Audio wires. I have other unshielded teflon isolated silver/gold wires and to me they sound the best.

I cannot give you a hint for your specific setup Tonny, but reasons for crackling could also be:

  • USB Cable too long
    for USB 3.x I’d use less than 2m, for USB 2.x less than 3m)
  • USB Cable quality
    tried two different 3m cables @ USB 2.0 -> one crackling sounds, one fine
  • Bad BIOS
    for example, some B550/X570 mainboards just received a BIOS update (see this report and the following quote)

With your help, we believe we have isolated the root cause and developed a solution that addresses a range of reported symptoms, including (but not limited to): USB port dropout, USB 2.0 audio crackling (e.g. DAC/AMP combos), […]


Thank you for your suggestions.
I have tried 2 different streamers, one with spdif and one with usb, so I think I can rule out usb ports and cables.
But I would like to know if Ifi Ipower x power supply is good enough for the dac. Maybe Khadas could chime in😉…

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That’s great, I think by ruling out the components we will eventually find the source of the problem.

The Ifi lpower x power supply should be able deliver the required power with ease. I can reliably power the Tone2 via USB 2.0, which offers a maximum of 500 mA @ 5V (if it is implemented following the USB 2.0 specification). The Ifi lpower x power supply supplies the connected device with up to 3,000 mA @ 5V.

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I want to make, what may be obvious to some, a comment about power supplies… all of them. Typically a given brand or model may be a well respected and known capable unit that can be relied on to supply clean, well regulated and sufficient-for-the-task power. That being said, no brand or model is a guarantee on its own when we are talking a specific, individual unit. Power supplies can suffer from the same frailties as other electronics. Individual components(i.e. capacitor, FET,) can go out of spec for a variety of reasons such as, age, heat, manufacturing flaw, line surges/spikes/sags, etc. Without an oscilloscope, or other testing equipment, some of these flaws can be hard to detect. So even though you have a nice brand and model, without a way to confirm it is OK, substituting a known good power supply will be your best bet. If a known good unit is not available, substitute a suitable supply and see if the symptoms change or disappear.
Sometimes adjacent circuits will induce noise, often it can be as simple as plugging to a different outlet on a different branch.
To rule out AC to DC supply issues, try powering with a suitable DC power bank.

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Does the problem get resolved?

Ensure with 5V input.

And for speaker setup, you might also need to check the input spec of the Amplifier, just ensure the input Vrms range higher then 2Vrms(usually yes), may be you can share us the model number of the Amplifier you are using.

Good day!

I haven’t had the problem in 6 days now. It has mostly happened when it was newly connected and not warmed up.
I have tested my streamer and Khadas dac at 2 friends homes, where it have had the crackle sound until warmed for 5-10 minutes by both friends.

My amp is Holton diy modules Hpa-nxl200 R4.2 combined with a buffer with opa627 op-amps.

The Ifi ipower x is definitely a 5v model. I have oscilloscope and dmm and I can test it for voltage and noise later on, to see if it has a failure.

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I have tested with 3 different power supply and I have some questions about the power led at the backside of tone 2 pro. Isn’t it supposed to indicate where it get its power from? Because if I plug an adapter wire (picture) at i2s usb-c it lights white, which indicate power from i2s, but I haven’t attached a power supply to the adapter wire yet. So how do I know where it get powered from?

The user manual explains the Power Priority:

And actually, if you check the schematic from the blog, the best LPS power input solution is to use dedicated pinout USBC cable with separately power sources for the pins of A4/A9 and B4/B9, and standard USBC cable with the both pins connected for same power source:

We will design a LPS for Tone2/Pro and launch with dedicated pinout USBC cable in the future.

Good day!


I also hear the same problem as @Tonny_Jensen. It isn’t my power supply nor cabling; and it’s very obvious when tracks change.

Also, where’s the fix for this reported phase problem? If Khadas wants to continue selling the Tone2 Pro, they need to remedy these problems sooner than later.

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I can notice this issue when the audio sample rate or the codec changes, 44.1kHz to 48kHz, FLAC to MQA, for example.

At the first moment, I thought that it related to Linux, but after this thread, I think not.

In general, for me, it’s not a big issue, due I normally listen to one artist’s album per time. But if you normally use playlists, yeah, it can be very inconvenient.

Regarding power priority.

I’m an electronic engineer and I have measured following:

Tone 2 pro will draw its power from either USB or power supply connected to I2S.
It will use power from which has the highest voltage, and not prioritize I2S if both connected.
So if USB voltage is 5.1v and I2S is 5.0v it will prioritize USB and not I2S.
If an USB cable only is attached to I2S, the LED illuminate white indicate power from I2S, even with no power supply attached to the I2S cable.
It seems like USB and I2S power lines are nothing but parallel junctions.