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Khadas Tone2 Pro Review (DAC & Amp)

phoenixdogfan

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With that volume control could this be used as a no frills preamp? Enough power to drive speaker amps in balanced mode?
 

Gabriel1

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Clock Mode............Adjustment?
There is a reference to adjusting the “clock” mode. I would very much appreciate being pointed towards some reference information to follow up on this.
 

madDog

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@amirm the price is 199$ for the dac/amp and $79.90 for 1m of cable. 20cm of cable for 49.90$. There is a listing on audiophonics.fr for us eu users, don't know about US, other then the offical site. If someone already mentioned all that, i apologize.
 

staticV3

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Clock Mode............Adjustment?
There is a reference to adjusting the “clock” mode. I would very much appreciate being pointed towards some reference information to follow up on this.
I'm guessing what they're referring to is the ES9038Q2M's MCLK.
A higher MCLK results in less noise, but more high-order harmonics:
2020-10-21_23-50-36.png
That measurement was done by user IVX.
 

flAked

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It's pretty easy to modify the K712 for use with balanced Amps. You can punch out the 3pin mini XLR connector and just glue in a 4pin mini XLR connector instead. The mod is completely seamless, though you'd have to source a 4pin mini XLR balanced cable somewhere. Those are not readily available.
Thanks for the info, that is a nice option to have. I kept my K501 alive for years with soldering but I don't feel like voiding my warranty right away at this point, maybe later :)

Another thing regarding Tone 2 and sample rate: after reading about the 48kHz problem I checked the Khadas Audio Dashboard and it always shows 48kHz under Status with the default output mode in Foobar, even if the source has a much higher sample rate.
If I change to ASIO out, it shows the correct sample rate ranging from 44.1 to 88.2 for my tested songs.
Should this concern me? Is the signal actually converted or is just the status fixed?
 
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amirm

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Which filters correspond to which on the graph? You have 8 results but there are only 7 selectable filters (page 11 of the manual).
I have no idea. :) I went into the menu and kept turning the knob until it switched and took a measurement. I suspect it wrapped around to the first one eventually. It is incredibly hard to navigate this device.
 
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amirm

amirm

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but even here one would wish for a PC interface for the settings.
Ah, this would be excellent. They already have a way to talk to the device to update its firmware. Wonder if they could use it to update settings.
 

TimW

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With that volume control could this be used as a no frills preamp? Enough power to drive speaker amps in balanced mode?
Unfortunately the volume knob only controls the headphone jack outputs. You could connect a power amp to one of the headphone outputs of course.
 

PeteL

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With that volume control could this be used as a no frills preamp? Enough power to drive speaker amps in balanced mode?
»driving » speaker amps require no power, it needs voltage, unfortunately we do not have max output voltages in this review, , let’s assume that the 4V balanced, 2V unbalanced on line outs equate 0 dBFS, but that would be an assumption and no proper spec sheet to be found in a quick search. If you ask me personally, I like to see more available voltage for something to be considered a proper preamp, but many people are happy feeding directly a power amp with these references, if the gain of the amp is sufficient.
Edit: an other contributor mentioned no volume control on line outs... odd, so not a preamp at all...
 
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staticV3

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»driving » speaker amps require no power, it needs voltage, unfortunately we do not have max output voltages in this review, , let’s assume that the 4V balanced, 2V unbalanced on line outs equate 0 dBFS, but that would be an assumption and no proper spec sheet to be found in a quick search. If you ask me personally, I like to see more available voltage for something to be considered a proper preamp, but many people are happy feeding directly a power amp with these references, if the gain of the amp is sufficient.
Edit: an other contributor mentioned no volume control on line outs... odd, so not a preamp at all...
I think this confirms 4/2Vrms as the max output:
Screenshot 2021-02-25 011423.png
 

frogmeat69

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@amirm I agree completely, the whole rotary knob double and triple clicking crap is maddening, and the lights don't help.
Otherwise, in low gain it seemed to drive the K371's nicely, and high gain, when I could figure it out, was very loud with them. Need to try my Sennheiser 650 and 660s with the 4.4 balanced cable.
 

jam

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Anyway, there is innovation on the back side as we have discussed before in the form of an RCA jack that can be used with an adapter cable to get balanced out as well:
View attachment 114513

Hopefully you can see the inner ring inside which gives you the third pin. Connector has a qualify look to it. I don't think you could have both balanced and unbalanced in this size package with any other option.

I went on Khadas' website and got this picture that shows the internal structure. It's patented by Khadas.
You can see more on its design here.

KhadasBalRCA.jpg
 
H

Hifihedgehog

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Can't really see the advantage of this one over 'premium dongles' with similar power like the Sparrow or the Lotoon S1. Creative Xfi Amp delivers also 370mW at 32Ohm and 55mW at 300 Ohm and has volume control buttons at half the cost.
For one, the Lotoo S1 has far worse SINAD of around 100-102 dB compared to the 117-118 dB of the Khadas Tone2. They are in totally different realms of measured performance.

---

I just want to set the record straight here so users aren't confused by some slightly off information.

The Luxury&Precision W2 is reaching 119dB SINAD: https://www.l7audiolab.com/f/information-update-of-lp-w2/
The thing is, the W2 is not available and it will very likely cost more. True, the W1 is available (not to be confused with the W2 charts that are also mislabeled with W1 in their chart images). The W1 measures at 105-109db unbalanced and 113db balanced which is a tad less than the Tone 2. The W1 already goes for $200 at HiFiGo. The W2, being the higher end model of the two, will likely go for a bit more. I'm assuming $300-$400--and I am very likely lowballing here seeing that Luxury & Precision sells $4000+ PMPs--with less features than the Tone 2.


The Meizu HiFi (116.8) and HiFi Pro (116.0) get pretty close, provided that you have clean 5V: https://zhuanlan.zhihu.com/p/94991395
Based on what I saw, I think you may be confusing SNR with SINAD in their charts. Plus, there I am seeing some crazy things in the decibel range from 106, 100, low 70s, and even 7 (what the heck?!) for the SINAD. In summary, there are some pretty funky numbers going on there that calls their testing methodology into question. The only 110+ dB numbers I saw at your link appear to be SNR which is not SINAD. Recall that Amir's testing showed sub-100dB SINAD for the Meizu HiFi. Similarly, he found ~100dB SINAD for its Pro older brother. That's in a totally different, minor league from the Tone 2 Pro's major league performance.


The 9038D is between 117.5 and 118.5: https://e1dashz.wixsite.com/index/9038d

I haven't seen any third-party measurements yet from Amir or WolfX-700, but I trust @IVX so I am strongly inclined to believe it measures as well as he claims. The 9038D doesn't have quite the connectivity and features that the Tone 2 brings to the table. However, for earphone users who demand world-class performance in absolutely the smallest possible, most portable package imaginable, the 9038D seems to be the ticket. (EDIT: Just emailed to order one!) It easily outperforms the Meizu and Luxury & Precision and undercuts the both of them. So if you need a dongle and don't need any of the Tone 2's added features, avoid Meizu and Luxury & Precision and just opt for the 9038D.

EDIT: The thing is, most devices these days have dirty USB power especially smartphones and tablets that are clawing up against the very fundamental limits to squeeze out that last little bit of wireless reception or range. As to the better numbers you PM'ed me, I disagree. Most of the alternative setups I have seen that claim higher performance for the Meizu use sterilized or idealized environments that filter out the USB noise well beyond anything real world. This is not most users here will be using unless they pay for and carry around an additional filtering device. And with a cheap portable audio dongle, carrying around an additional power filtering device is not really practical or economical. tl;dr: @staticV3, we'll just have to agree to disagree here. :)
 
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solderdude

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Why not use 196Khz with all DACs? this would move the "problem" far outside the audible range.

Because most recordings are 44.1 and most video 48kHz ?

One would have to upsample the files yourself and the used filter in the upsampler could be worse than the one in the DAC's digital filter itself.
The 24kHz low pass (when steep enough) isn't really problematic when using music. It can be on the test bench.

196kHz doesn't exist b.t.w. it is 96kHz or 192kHz ;)
 

Lambda

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One would have to upsample the files yourself and the used filter in the upsampler could be worse than the one in the DAC's digital filter itself.
The filter can also be better (especially if the dacs filter is bad like in this case) and the user can decide what filter/up sampler/ditter to use.
After all its "just algorithms" and i don't see why i they would run better in real time with low latency the DACs DSP

Some up samplers are CPU power demanding and would if all run better on a PC then in the DAC.

The 24kHz low pass (when steep enough) isn't really problematic when using music. It can be on the test bench.
Not relay problematic is also not perfect and not as good as it could be.
Using higher sample rates is basically free and doesn't hurt.

196kHz doesn't exist b.t.w. it is 96kHz or 192kHz ;)
Yes of cause :facepalm:

and most video 48kHz
Oh i thought bluray is 192khz.
 
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