Audio Science Review - Measurements of Khadas Tone Board DAC
Updated: Mar 9, 2020
This is a review and detailed measurements of the Khadas Tone Board DAC. It is on kind loan from the company. The retail price on Amazon is USD $99 including free shipping.
As the name indicates, this is a bare board DAC:
Don't confuse this with Raspberry Pi boards though. This is a complete DAC and doesn't need a host to operate. It is just like any other desktop DAC except that it doesn't come with a case.
The Khadas Tone Board is powered and accessed through the USB port and S/PDIF. For my review, I only tested the USB input.
Output as you see is through a pair of RCA jacks that have a great high-quality look and feel (as does the S/PDIF one). It would be at home in DACs at much higher prices.
Khadas sells two versions of this board, one of which mates with their host processor to make a complete networked DAC and player. They were kind enough to send me the host which I will review later.
Let's get into measurements and see how well it does.
As usual, we start with our dashboard view:
I must say, I was not prepared for such excellent performance from such an unassuming board! Essentially 110 dB SINAD (signal above noise and distortion) in a $99 DAC? That is most excellent:
I should have of course paid attention to the web page for this product: https://www.khadas.com/tone
Right there is the same dashboard measurement with the same Audio Precision APx555 analyser I have with identical response!
Their THD+N is 0.000337% and mine is 0.000331%. Wow, what consistency!!!
This is a company that does things right, measuring and verifying designs.
Continuing on with jitter and noise we get:
There a lot of little spikes visible but that is partly due to very low noise floor which reveals more of these. Worst case spike is below -130 dBFS which is well below any threshold of audibility.
Here is intermodulation distortion versus level:
Here, we have typical response similar to what we get from other desktop DACs using ESS' later DAC chips.
Dynamic Range comes next:
This is very good but a bit shy of their numbers. This measurement though is very sensitive to such things as ground loop so in other situations it may be possible to get close to the 120 dB number they post.
I have been asked for crosstalk measurements so here it is:
The spec better than 127 dB and it definitely seems to be there at almost all frequencies.
Crosstalk usually increases with frequency as we see in Schiit Modi 3 graph but here, the Khadas Tone Board maintains the same level throughout audio band which is excellent.
Lastly, we have linearity test:
I like to see less than 0.5 dB of deviation at -120 and Khadas Tone Board easily sails through that criteria.
Khadas contacted me and joined the forum immediately after someone mentioned this board as something to test. They quickly sent me the samples but due to my busy schedule, I was remiss in not testing it until now. I regret that delay seeing how well their product did in my testing.
The Khadas Tone Board is a high performance DAC and a bargain price. It is exceptionally well engineered and easily earns my highest recommendation!
Get your own case for it and tell your friends you designed it. :)
That Khadas is active on forums and ready to support their owners is a fantastic bonus.
Founder, Audio Science Review
Founder, Madrona Digital
Contributing Editor, Widescreen Review Magazine