Topping D900 DAC Review

[Toxmarz]

This is a review and detailed measurements of the Topping D900 discreet "1-bit" balanced smart DAC with PEQ. It was sent to me by the company and costs US $1,799.
View attachment 517828
The D900 comes in the most prestigious clothing Topping uses. It gives a feeling of luxury which I like. Touch screen UI is provided for manipulation of setting (as well as a remote which I did not need to use). Back panel shows elimination of RCA output which I am totally fine with:
View attachment 517829
Instead, we get variable and fixed outputs. Dual optical and coax inputs are provided for those of you with many such inputs. Trigger is now standard seemingly on all Topping products which is much appreciated. It allows one button turn on of your entire system.

As specified, the incoming PCM samples are upsampled to one bit which can then be converted to analog using a simple low pass filter. Parametric EQ completes the picture.

Topping D900 DAC Measurements
The D900 benefited by the tune of 0.5 dB after a few minutes of warm up to produce some of the best noise+distortion numbers I have measured:
View attachment 517830
View attachment 517831

The D900 has copious amount of drive, going as high as 12.3 volts!
View attachment 517832
This allows you to use your power amp at its lowest gain setting, boosting overall system signal to noise ratio. Speaking of that, the dynamic range is excellent:
View attachment 517833
It goes up about 1 dB at max volume (not shown).

Multitone shows state of the art levels of distortion:
View attachment 517834

As well as with a 50 Hz signal into 600 ohm load, per stereophile protocol:
View attachment 517835

Slight error seen at very low amplitude in our IMD sweep:
View attachment 517836
But then becomes noise dominated and quite low at that.

We see the same small blemish in our linearity test:
View attachment 517837

The noise floor is extremely low and clean in jitter test:
View attachment 517838
Which then shows up a couple of inconsequential tones at -140 dB. The spikes on the left are part of the signal and are resolved incredibly well down to 24 bit LSB.

Filter attenuation is excellent:
View attachment 517839

With the tiniest bit of droop at 20 kHz (0.2 dB):
View attachment 517840

Wideband noise+distortion shows elevated levels considering what we have measured so far:
View attachment 517841

But that has an explanation in the form of ultrasonic noise shaping:
View attachment 517842

So not an audible concern.

Conclusions
As custom DAC implementations go, the D900 is the most perfect I have seen. It represents a heroic effort to near match state of the art, integrated DAC silicon. In other words, you get the buzzword of "discrete 1 bit" DAC with almost no penalty. Getting this level performance out of huge number of individual components is not easy and shows excellent engineering prowess.

Price is up there with respect to IC based solution. But is a "bargain" compared to high-end DACs with similar architecture but usually with worse performance.

I am going to recommend the Topping D900. If you want a custom DAC, this is it.
-----------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

Toppings answer to Whataboutism. Ok here it is as good or better than anyone else's implementation and cheaper. Now shut up and let us getting back to making the really good stuff that real world people need.

 

[srkbear]

Have been looking forward to this; it appeared that Topping went for broke with this one. However, other than some FOMO over missing out on the integrated PEQ, I still haven’t encountered anything to entice me to part ways with my d90se. Ya’ll finally convinced me awhile back that I’m unlikely to hear anything better than “perfect”. I remain engaged out of scientific curiosity, but my approach at this point is to admire but not acquire. It’s a peaceful place to be done…

 

[Redman43]

I think this device is a definitive answer to everyone who doubted Topping's engineering expertise. If you've spent any time on audio forums, you know Topping has been dismissed for years as a company that simply sources the latest chip and slaps on −100 db of negative feedback. That was always the go-to criticism: "That's not real engineering. They just grab the newest DAC chip, pile on negative feedback with cascading op-amps, and call it a day. They don't actually know what they're doing. They're not a real engineering company. They don't have the expertise to design a 1-bit DAC or an R-2R DAC."

Basically this is a big fuck you from Topping to haters and showing others(who sell their dacs for 14000$) how it's done. I don't think you are the target audience here. They beat Chord in their own game while also making the dac 8 times cheaper.

Well said

 

[Milt]

@Blockader & Redmman43.
Well said indeed.

Topping & the other Chinese companies offer too many options that are redundant.
Sorry but wtf are you bitching about?
So, you like having fewer options & choices. Are you befuddled with the overwhelming choices?
Too bad.
These brilliant people are demonstrating what is possible with different legit methods of sound reproduction.
Not to mention that they do it an honest price.
We're spoiled for choice.
Pick your preference & be happy

 

[michaelahess]

In case these are asked seriously:

In the opamp world, there are integrated circuits that cost a few dollars which internally have dozens of transistors. Nonetheless, companies like Muses and Sparkos have made devices on PCBs with separate discrete transistors, capacitors and resistors. These are called discrete opamps.

DACs typically use integrated circuits from TI, AKM or ESS. These chips have hundreds of transistors and capacitors inside them, including digital logic, the DAC bits buckets, output filters, etc. In this device, Topping has designed their own (very large) DAC circuit board with all of these components broken out instead of using a single chip implementation.

There is no reason that discrete proprietary devices should sound better but some audiophiles like it.

Regarding single-bit: DACs get fed information at a certain sample rate (e.g. 48 khz) and bit depth (e.g. 16 bits). However, if you have a 15-bit DAC working at 96 khz, you can send the same data. A 15 bit DAC wouldn’t be able to output the even numbers from a 16 bit DAC (where the least significant bit is not zero) but you are operating at double the clock rate so you output the number rounded up one cycle and rounded down the second cycle. This makes a -90 dB noise at 48 khz, but the output filter will quash that.

It is quite easy to demonstrate that each doubling of frequency can remove at least a bit of required sample depth. The math is complex (as all delta-sigma designs rely on noise shaping), but by operating a DAC at a few mhz, the full dynamic range and frequency range of a 16/44.1 signal can be achieved with a single bit DAC.

The advantage of a 1-bit DAC is that for a multi-bit DAC you need precision matched resistors to be able to make the various voltages. A 1 bit DAC uses a single voltage across a single transistor feeding a single capacitor. This single device will always match itself. There is also a cost advantage for single-bit designs but this is canceled out by Topping doing a discrete circuit.

Exactly what I wanted to know, thank you! I assumed custom was related to opamp rolling or something like that, but it's literally a custom built dac from the component level. That's wild.

With the size of components these days, I would assume an integrated DAC chip would be WORLDS better in regards to emi, noise, whatnot.

I'm my 45 years, I don't think I've ever heard the term 1-bit DAC. As a sysadmin, I want MORE bits!

Thank you for the explainer!

 

[Roland68]

Exactly what I wanted to know, thank you! I assumed custom was related to opamp rolling or something like that, but it's literally a custom built dac from the component level. That's wild.

With the size of components these days, I would assume an integrated DAC chip would be WORLDS better in regards to emi, noise, whatnot.

I'm my 45 years, I don't think I've ever heard the term 1-bit DAC. As a sysadmin, I want MORE bits!

Thank you for the explainer!

1-bit DACs have been around as long as CD players, over 35 years, so they're nothing new.
As a system administrator, you're probably familiar with serial data processing and its advantages, such as SATA, SAS, PCI Express, Ethernet, USB, DVI, HDMI, WLAN, Bluetooth, etc...

 

[Robbo99999]

What are the PEQ options, would have been to have been included in the review. I'll read the thread to see if that's answered. Expensive DAC I suppose, so who cares about the 1bit advertising aspect, but the PEQ is interesting.

 

[misterdog]

If only it weren't for the problem with warranty claims (which depends on where the device is purchased) and the lack of repair guarantees for the next 10-20 years.....

Topping products are available in the UK with a 2 year warranty from the retailer.

Name any products with a 10-20 year warranty. The only audio product I know of with a good warranty is the Benchmark AHB2 amp, which comes with a five year warranty in the US, but only two years in the UK.

I've just bought a coffee grinder which was available with a 1/2 or 3 year warranty, the longer the warranty the higher the price.
Those who really think a 20 year warranty is required can take out their own insurance, at their expense, that's how market driven capitalism works.

 

[emmodad]

In case these are asked seriously:

In the opamp world, there are integrated circuits that cost a few dollars which internally have dozens of transistors. Nonetheless, companies like Muses and Sparkos have made devices on PCBs with separate discrete transistors, capacitors and resistors. These are called discrete opamps.

DACs typically use integrated circuits from TI, AKM or ESS. These chips have hundreds of transistors and capacitors inside them, including digital logic, the DAC bits buckets, output filters, etc. In this device, Topping has designed their own (very large) DAC circuit board with all of these components broken out instead of using a single chip implementation.

There is no reason that discrete proprietary devices should sound better but some audiophiles like it.

Regarding single-bit: DACs get fed information at a certain sample rate (e.g. 48 khz) and bit depth (e.g. 16 bits). However, if you have a 15-bit DAC working at 96 khz, you can send the same data. A 15 bit DAC wouldn’t be able to output the even numbers from a 16 bit DAC (where the least significant bit is not zero) but you are operating at double the clock rate so you output the number rounded up one cycle and rounded down the second cycle. This makes a -90 dB noise at 48 khz, but the output filter will quash that.

It is quite easy to demonstrate that each doubling of frequency can remove at least a bit of required sample depth. The math is complex (as all delta-sigma designs rely on noise shaping), but by operating a DAC at a few mhz, the full dynamic range and frequency range of a 16/44.1 signal can be achieved with a single bit DAC.

The advantage of a 1-bit DAC is that for a multi-bit DAC you need precision matched resistors to be able to make the various voltages. A 1 bit DAC uses a single voltage across a single transistor feeding a single capacitor. This single device will always match itself. There is also a cost advantage for single-bit designs but this is canceled out by Topping doing a discrete circuit.

"hundreds of transistors" >> probably millions

"for a multi-bit DAC you need precision matched resistors" >> yes; historically major issue; today still not a party but approaching closer to trivial in on-chip implementation. However, oversampled noise-shaping converters obviate the need and are far more amenable to high-volume / high-yield / low cost IC implementation, so why bother.

"15 bit DAC wouldn’t be able to output the even numbers from a 16 bit DAC" >> please clarify your meaning (perhaps just semantics)? 15- vs 16-bit DAC IC means that range from +Vmax to -Vmax is quantized with 2^15 levels vs 2^16 levels. 16-bit "good data word" input to a 15- vs 16-bit level of performance (ie distortion/error) DAC IC is another story


edit: performance > level of performance

 

[Roland68]

Topping products are available in the UK with a 2 year warranty from the retailer.

Name any products with a 10-20 year warranty. The only audio product I know of with a good warranty is the Benchmark AHB2 amp, which comes with a five year warranty in the US, but only two years in the UK.

I've just bought a coffee grinder which was available with a 1/2 or 3 year warranty, the longer the warranty the higher the price.
Those who really think a 20 year warranty is required can take out their own insurance, at their expense, that's how market driven capitalism works.

Sorry, you misunderstood me. Perhaps that's because I'm not a native English speaker and chose the wrong term.
I mean, a repair guarantee for a period of at least 10, ideally 20 years. Ideally with fixed rates or upper limits.

I don't want my device, which cost almost €2000, to become a paperweight after 3 or 5 years, or for repair costs to be so high that it's not worth it.
For example, Violectric/Lake People repairs even 30-year-old devices at absolutely fair prices.

A major problem with Topping, and other similar manufacturers, is that they give absolutely no thought to potential repairs during the development and planning of their devices. Otherwise, they wouldn't use extremely cheap and problematic very small SMD components in so many places.
This is unacceptable for me in a €500 device, even less so in a €1000 one, and in this price range, it's an absolute no-go.
Topping consistently demonstrates excellent development, but they completely fail in this discipline. As they say in sports, a perfect freestyle routine, but a failure in the compulsory exercises.

 

[emmodad]

I still don’t see the point, but at least the esotericism doesn’t come at the cost of performance, only price.

It's not about being esoteric, or different (although those can be marketing fodder)

It's purely about the high-end commercial DAC IC market reaching saturation/stasis; Large corporate IC vendors not seeing interesting volumes and hence business cases to justify continuing advanced development to serve audiophilia; and Topping therefore taking control of their destiny in high-performance audio DAC (as in circuit-level digital-to-analog conversion functionality) implementation.

The number of IC manufacturer single-chip commercial market solutions which meet performance metrics of top AKM / ESS / TI / ADI / Mediatek / etc is small; and got smaller as consequence of the AKM factory fire. Topping bought up a large lot of the remaining best AKM devices primarily for their DX9 company anniversary "statement" product; but that lot was going to run out...

IIRC, AKM "replacement" is a somewhat sensitive (board layout, high-speed interconnect, etc) 2-device chipset solution. Until AKM manages to consolidate those two devices on a single die (aka single piece of siicon inside a single package) – IF it's possible and IF they decide there's a profitable business case to actually do it – then a multi-device solution will be more expensive (not just chipset cost, but layout, board real estate, power supply considerations, decoupling caps, etc, etc). Of course, AKM could sell it as a loss leader as carryover to availability of a single package device (IF they've decided to do that, etc etc); but their customers would have to be willing to do a complete product revision (board/system redesigns).

If a product manufacturer (Topping) can create a solution which is totally under their own control and for their particular cost/volume roadmap meets or exceeds performance metrics of top AKM / ESS / TI / ADI / Mediatek / etc IC supplier devices... then Topping can free themselves (insignificant volumes in the grand scheme of things in the semiconductor world) from dealing with those Large Corporate IC Suppliers. Doesn't matter if Topping's solution uses resistors, switches, and active electronic devices; or bananas, toothbrushes, and chocolate truffles: if it meets performance / cost / power metrics, then it's good.

it sure looks like Topping may be using their same in-house oversampled noise-shaping D/A conversion solution (the so-called discrete 1-bit PSRM decoding architecture discussed in this thread) in both the D900 ($1800) and the DX9 discrete (2nd generation of DX9, after supply of best AKM DAC IC ran out; $1300). Back panels look to be identical, feature set / performance similar/identical), quite possibly the same (or minor revision) circuit board and internals...

Topping could start a new revenue stream by licensing the (hopefully-patent-protected) intellectual property of their design.

Perhaps someone could supply @amirm with a DX9 discrete for review. That could yield an interesting comparison with the D900.


edit: added final line

 

[emmodad]

Exactly what I wanted to know, thank you! I assumed custom was related to opamp rolling or something like that, but it's literally a custom built dac from the component level. That's wild.

With the size of components these days, I would assume an integrated DAC chip would be WORLDS better in regards to emi, noise, whatnot.

I'm my 45 years, I don't think I've ever heard the term 1-bit DAC. As a sysadmin, I want MORE bits!

Thank you for the explainer!

"I'm my 45 years, I don't think I've ever heard the term 1-bit DAC" >> goog on "oversampled noise shaping converter" which have been a thing in telecoms since at least the 1960s; audio world late 1970s onward. See ie the 1980s dbx Model 700 Digital Audio Processor

(fun fact: I was blessed to know the dbx folk well; I still have a copy (somehere... and sadly only mp3) of one of their great dbx 700 demo tracks performed by the in-house band, the "dbx Dynamic Rangers"! Sound of a nickel (US 5-cent coin) dropping onto a hard surface is awesome...)

 

[emmodad]

Topping products are available in the UK with a 2 year warranty from the retailer.

Name any products with a 10-20 year warranty. The only audio product I know of with a good warranty is the Benchmark AHB2 amp, which comes with a five year warranty in the US, but only two years in the UK.

I've just bought a coffee grinder which was available with a 1/2 or 3 year warranty, the longer the warranty the higher the price.
Those who really think a 20 year warranty is required can take out their own insurance, at their expense, that's how market driven capitalism works.

Bryston analog products: 10 years

(not intended to be snide. You're absolutely correct. exceptioon rather than the rule)

 

[TurtlePaul]

"15 bit DAC wouldn’t be able to output the even numbers from a 16 bit DAC" >> please clarify your meaning (perhaps just semantics)? 15- vs 16-bit DAC IC means that range from +Vmax to -Vmax is quantized with 2^15 levels vs 2^16 levels. 16-bit "good data word" input to a 15- vs 16-bit performance (ie distortion/error) DAC IC is another story

Yes, a DAC with 2^15 output voltage levels, but operating at 2x the sampling rate can output a signal with 2 ^16 possible levels. Many of the earliest CD players had 14-bit DACs with 4x upsampling to play back the 16-bit signal.

1-bit DACs take this to the logical extreme by having DACs with a single bit of precision but operating at much higher sample rates - for example 2.8 mhz for SACD delta-sigma encoding up to 22.6 mhz for DSD512 encoding.

Many of the best DACs today are 3-bit or 4-bit thermometer DACs which are operating at very high sample rates.

 

[emmodad]

Yes, a DAC with 2^15 output voltage levels, but operating at 2x the sampling rate can output a signal with 2 ^16 possible levels. Many of the earliest CD players had 14-bit DACs with 4x upsampling to play back the 16-bit signal.

1-bit DACs take this to the logical extreme by having DACs with a single bit of precision but operating at much higher sample rates - for example 2.8 mhz for SACD delta-sigma encoding up to 22.6 mhz for DSD512 encoding.

Many of the best DACs today are 3-bit or 4-bit thermometer DACs which are operating at very high sample rates.

Indeed.

regarding those early 14- and "16"-bit DAC ICs of the 1980s, you might enjoy this: how Studer coaxed better performance from the Philips TDA1541

 

[boXem]

in-house oversampled noise-shaping

It's a chip they buy.

 

[Phorize]

Topping products are available in the UK with a 2 year warranty from the retailer.

Name any products with a 10-20 year warranty. The only audio product I know of with a good warranty is the Benchmark AHB2 amp, which comes with a five year warranty in the US, but only two years in the UK.

I've just bought a coffee grinder which was available with a 1/2 or 3 year warranty, the longer the warranty the higher the price.
Those who really think a 20 year warranty is required can take out their own insurance, at their expense, that's how market driven capitalism works.

RME ADI- FS Pro BE is more or less the same price as the D900 in the UK but has an ADC and a 5 year warranty. Not a discrete DAC of course but stiff competition IMO.

 

[Roland68]

RME ADI- FS Pro BE is more or less the same price as the D900 in the UK but has an ADC and a 5 year warranty. Not a discrete DAC of course but stiff competition IMO.

Even though both devices are priced in the four-figure range, the overlap in customer base is likely negligible.
Buyers of the D900 want a more exclusive DAC/R2R DAC, while buyers of the RME ADI-FS Pro BE primarily purchase the device for its functionality and reliability.
Therefore, competition is rather rare.

However, the RME device is discontinued and hardly available new anymore. It will be interesting to see what RME presents as its successor.

 

[Roland68]

"I'm my 45 years, I don't think I've ever heard the term 1-bit DAC" >> goog on "oversampled noise shaping converter" which have been a thing in telecoms since at least the 1960s; audio world late 1970s onward. See ie the 1980s dbx Model 700 Digital Audio Processor

(fun fact: I was blessed to know the dbx folk well; I still have a copy (somehere... and sadly only mp3) of one of their great dbx 700 demo tracks performed by the in-house band, the "dbx Dynamic Rangers"! Sound of a nickel (US 5-cent coin) dropping onto a hard surface is awesome...)

Anyone who dealt with CD and SACD players in the 90s and 2000s couldn't have missed 1-bit DACs.
However, the buzzwords for them were delta-sigma converters, bitstream, mesh, etc.
Among them were also some DACs where 4 or 5 single-bit converters worked in parallel, and a few other variations as well—a confusing jumble with an extreme amount of useless and unsubstantial marketing hype.

 

[SoySalsaPicante]

I wonder about the reliability of these. I have now owned and returned two D90 III Discrete DACs due to various problems with them. I gave up and simply got a D90 III Sabre, which is absolutely flawless in operation.