Gustard X18 Review (Stereo DAC)

[Ron Texas]

I think the larger display is pretty significant. The option of using 5V output is interesting also. Support for MQA Full Decoding on all inputs instead of only USB may be of interest to some folks. The X16 can only do MQA Rendering on S/PDIF and I2S inputs.

I'm happy with my X16, but if I was in the market for a new DAC today, the extra $250 for the X18 would not be difficult to justify.

I suppose it depends on what's important to the buyer. The sub integration features of the new DAC from MiniDSP interest me.

 

[kopczas]

MiniDSP interest me.

I would love to see measurements of these new devices. MiniDSP shows only BT capabilities , and typical catalog data. I wonder how it actually works with DSP on . Analog in to Analog out thou DSP.

 

[amirm]

I retested the unit using its own volume control:

As you see, it doesn't attenuate as much giving it a slight unfair advantage compared to other DACs. Running with it anyway, it moves up to #2 position:

 

[kiyu]

You are right bro, there's no 'perfect software', but we are always trying to do the best in development. Big bugs were killed before batch production.
Once new bugs noticed by users, we will keep tracking and solve it as soon as possible. All the firmware updates would be released and stored on Internet. This issue of X18 is noticed before batch productions' delivery, so everyone of you can buy the fixed one.

The support will last at least one year after production stopped.

so in case that a new bug is found, is possible and easy for users to update the firmware without any specific/extra tool or need to open the DAC right? just like windows installer and that's it?

 

[KMO]

Am I understanding some of the above discussion correctly in that these sorts of DACs often have digital (ie pre-DAC) volume controls rather than analogue? That's certainly a potential downside if you're relying on that volume control so you can just drive a pre-amp. Immediate loss of significant bits. Not something I'd really considered.

In terms of testing protocol, always adjusting the digital input to get constant output does seem inappropriate - you're throwing bits away before even reaching the device, particularly penalising high-output devices. The device under test should be asked to adjust volume if it provides the facility. If it has digital volume, that should be no different to changing the input, but it gives the device a chance to show the potential benefit of real analogue volume, and opens up the scope for revealing problems with the device's attenuation, whether analogue or digital.

 

[Vhond]

I hope @GoldenOne (it seems he's not active on this forum anymore?) will review it at his Youtube channel

 

[amirm]

Am I understanding some of the above discussion correctly in that these sorts of DACs often have digital (ie pre-DAC) volume controls rather than analogue? That's certainly a potential downside if you're relying on that volume control so you can just drive a pre-amp. Immediate loss of significant bits. Not something I'd really considered.

Most of the time the volume control is internal to the DAC and works very well. When you reduce levels, you always lose dynamic range so "loosing bits" is not an avoidable thing.

In almost every case that a volume control is put after the DAC, performance is reduced. This DAC is one of the few exceptions.

 

[kopczas]

This DAC is one of the few exceptions.

So there is another volume control other then built-in in DAC itself?

 

[KMO]

When you reduce levels, you always lose dynamic range so "loosing bits" is not an avoidable thing.

Except that the noise sources will be in different places. Noise in the DAC would be attenuated by a post-DAC volume control along with the signal, so if there's less noise post-DAC, you lose less dynamic range by post-DAC volume - hence the win here.

 

[KMO]

So there is another volume control other then built-in in DAC itself?

This has a post-DAC digitally-controlled analogue attenuator (as you would find in a combined DAC+pre-amp+power-amp box like an AVR).

 

[kopczas]

post-DAC digitally-controlled analogue attenuator

Is this ESS feature or Gustard solution?

 

[KMO]

Is this ESS feature or Gustard solution?

Gustard. The ESS chip has a pre-DAC digital volume control, and its analogue output level is fixed at about 0dBFS = 1.1Vrms if I read the datasheet correctly, so you need gain stages. Gustard has put in analogue controls there rather than fixed gain.

 

[pickyAudiophile]

When I use streaming services like Qobuz on my PC I prefer DACs which can be adjusted in volume by Windows OS even when output is set into "WASAPI exclusive mode". Just as a matter of convenience....no matter what about word length (bit) truncation or noise.

I used to own the Gustard A18 and that one was not adjustable in "WASAPI exclusive mode", whether windows volume set to 1% or 100% - made no difference. (I'm not talking about hardware volume control from that device, just to clarify, of course that one worked but I preferred do leave it at maybe -15dB and do the rest by OS' volume control.)

I never managed to predict that prior to purchasing a DAC. It's like trial-and-error each time. The X18 any different?

 

[bigLP]

Does this gustard have discrete output devices or ICs or op amps? I know I have heard people debate the use of discrete devices by gustard, where topping uses op amps. The point has been made that it is tough to get top notch measurements with discrete devices. Is that the case for this dac? It test well despite the discrete components?

 

[gustard]

Does this gustard have discrete output devices or ICs or op amps? I know I have heard people debate the use of discrete devices by gustard, where topping uses op amps. The point has been made that it is tough to get top notch measurements with discrete devices. Is that the case for this dac? It test well despite the discrete components?

X18's output stage is built by eight OPA1612. There is no discrete output.

 

[Mrgoogle]

This is a review and detailed measurements of the Gustard X18 Balanced USB DAC with Bluetooth. It was sent to me by their seller, Shenzhenaudio and costs US $749.

View attachment 172199

As you see style is very much the same as other Gustard products. I like the high resolution display with larger volume indicator.

Back panel shows the usual connections:

View attachment 172200

Gustard X18 Measurements
Let's start with our usual dashboard with balanced output with digital input adjusted by -2 dB to get nominal 4 volt output:
View attachment 172201

That is extremely good performance. The second harmonic dominates distortion profile but it is down -135 dB (25 dB below threshold of hearing). This easily qualifies X18 as state-of-the-art, placing it in top 3 DACs ever measured:
View attachment 172202

EDIT: post these measurements, the company advised that the X18 has a high performance post DAC attenuator and as such, performs better using its volume control than attenuating the input signal. So I tested that with volume set to -2:

View attachment 172530

As you see, the attenuation is slightly less than making the same change in the source. I usually allow 0.1 volt variation but this is a bit much as far as fairness to other DACs. Still, going with it, the X18 changes position to #2 best DAC ever tested:
View attachment 172531


Switching to unbalanced RCA output, we still get superb performance:

View attachment 172203

Allowing the output to get up to 5.4 volt, we get even better performance due to increased dynamic range:
View attachment 172205

Dynamic range is exceptional:
View attachment 172419

Intermodulation+noise performance is superb as expected:

View attachment 172206

Jitter test over USB is great:
View attachment 172207

But there is some inconsequential jitter components if you use Toslink or Coax:

View attachment 172208

Linearity is nailed:
View attachment 172210

As usual, you have an array of reconstruction filters to choose from:
View attachment 172211

Using default L-FAST, we get extremely clean wideband distortion+noise performance:

View attachment 172212

Edit: forgot the multitone test initially:

View attachment 172343

Conclusions
I live for happy days like this: another instrument grade, exceptionally well engineered audio product in the form of X18. It is clear a ton of effort has gone into providing full transparency to input signal. Yes, the cost is up there but if you want the best, you now have one more option.

It is my pleasure to recommend the Gustard X18 DAC.

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hi Amir , one question rise up , what did you have for load at output in THD+N Versus Frequency ??

 

[m8o]

Ah, another thing that does the thing that can't be distinguished from many other things, including the previous thing in the series of things (the x16)

Right? Lol

Asking widely, anyone figure out why this is worthy of +2 and $250 ($300?) over the X16? Honest. Not being facetious. What am I missing?

 

[dsnyder0cnn]

Right? Lol

Asking widely, anyone figure out why this is worthy of +2 and $250 ($300?) over the X16? Honest. Not being facetious. What am I missing?

For me, the bigger volume indicator means the X18 can be used as a digital preamp while the X16 is not great for that since you can't see the volume setting from more than two feet away if you're over 50. 5V output capability is nice if your amp or preamp supports it. Some folks might care about full MQA decoding on all inputs…not just USB (eg., you can connect a CD transport and decode MQA CDs). If the output impedance is less than 300Ω, that would be nice too, but I've not seen that spec published. Slightly better specs, even if not audible, are welcome.

Add all that up, and I'd gladly pay the extra $250 if I did not already own an X16.

 

[gustard]

For me, the bigger volume indicator means the X18 can be used as a digital preamp while the X16 is not great for that since you can't see the volume setting from more than two feet away if you're over 50. 5V output capability is nice if your amp or preamp supports it. Some folks might care about full MQA decoding on all inputs…not just USB (eg., you can connect a CD transport and decode MQA CDs). If the output impedance is less than 300Ω, that would be nice too, but I've not seen that spec published. Slightly better specs, even if not audible, are welcome.

Add all that up, and I'd gladly pay the extra $250 if I did not already own an X16.

The output impedance is 100Ω. We haven‘t thought it can be a advertising feature

 

[amirm]

hi Amir , one question rise up , what did you have for load at output in THD+N Versus Frequency ??

Hi there. It is high impedance (200K for balanced, 100K for unbalanced).