Pricing

In the UK, the D900 is available from a selection of retailers for £1799. It can be ordered online from some authorised retailers and there should be no issue securing one from any location in the UK. In the USA the D900 is available for $1799, reflecting a larger market and different sales model. In Australia it is available for $3099.

It is possible at the time of writing to find online locations shipping the D900 direct from the Far East, usually with a reduction over the UK retail. These units will not have a UK warranty however so it would be best to be careful about doing so.

Design

• Solid and understated
• Small but informative display
• Remote control
• Matching headphone amp
• Some gremlins connecting up

The D900 is a three quarter width design at 330mm. It is perfectly possible when you unbox it from the (really well thought out) packaging that you might find it slightly underwhelming but I suspect that feeling should pass pretty quickly.

The D900 arrives looking sober to the point of minimalist. I have to say I feel this is the right approach and I really like it. The D900 has a quiet seriousness to it that should sit in most systems very effectively. The standard of build is excellent and it whispers rather than shouts a level of quality. It is exclusively available in silver.

The main focal point on the front panel is a small display. This can show input and incoming sample rate information as well as settings menus and both an old fashioned output VU meter and more modern graphic equaliser style interface. The display isn’t terribly large and can’t be read at a huge distance but it’s useful to have when setting the D900 up.

There is a small but no less sturdy remote handset too. This has been a bit of a mixed bag for me in use; there have been points where it hasn’t been responsive at all, but it’s useful to have; particularly if you intend to use the D900 as a preamp in your system. The remote also combines with the display to simplify settings menu access although the menu tree for this is not as intuitive as it could be.

As hinted at earlier, the D900 is a DAC and not a DAC headphone amp (and this is why the D900 is a ‘D’ and not a ‘DX’). If you want to go all in, Topping makes the entirely analogue A900 to partner the D900 and this is a formidable looking device with sockets for any occasion.

It does mean that the D900 isn’t as all singing and dancing as some of its more affordable brethren but allows it to focus on a smaller range of tasks. How much of an issue this will be to you is almost certainly going to depend on what equipment you have kicking around already.

Getting the D900 up and running wasn’t completely straightforward.  It would not connect at all to the Chord Electronics 2Go/2Yu streaming head unit over USB and fought me for some time to connect to the usually viceless Eversolo T8.

First it didn’t want to be seen and then, once it was, it proceeded to lock incorrectly, resulting in garbled, high speed sound. Once it was sorted, it stayed sorted but I had to put the effort in.

Specification

• Wholly bespoke digital to analogue decoding
• Wide selection of digital inputs…
• …but slightly more limited outputs
• On board EQ
• Preamp functionality

The principle focus of the D900 is its decoding. It isn’t the first time Topping has implemented this system; that was the D90 III Discrete which uses a simplified version but the D900 takes it to its logical conclusion.

The system is called PSRM which stands for Precision Stream Reconstruction Matrix. It is a ‘1 bit’ system (a notional ideal that dates back to the early days of CD where, so long as the signal is handled correctly before it reaches the actual decoder, it boasts the scope for excellent measured performance) and incorporates discrete 1-bit modules that convert digital audio streams into analogue voltage by turning each audio sample into a very fast train of 1-bit pulses.

The waveform is in turn defined by the density of the pulses and it’s shaped by an analogue reconstruction filter. This is the same as an off the shelf  Delta Sigma DAC but Topping controls the entire process rather than buying in a chip that gets on with it. Where the D90 III had 16 of these modules, the D900 has 32 of them.

These modules are powered by a bespoke power supply that employs a voltage-reference power supply that is purely resistive. It uses digital switching logic operating at the nanosecond level for maximum performance.

The business of turning this signal into a usable output is undertaken by a new, proprietary I/V conversion circuit composed of low distortion integrated op-amps and ultra-low-noise discrete components carefully selected after repeated testing.

If this all makes your eyes glaze over, you can focus on the fact that the claimed measurements (that the D900 has achieved when independently measured) are state of the art.

This formidable hardware is made available to an extensive selection of inputs. There are seven wired connections; two optical, two coax, one AES, one USB (on both USB-C and B connections) and an i2S connection; a very high performance option derived from pro audio.

These are augmented by Topping’s excellent Bluetooth implementation. Sample rate handling via USB and i2S is PCM to 768kHz and DSD to 512 with other connections having lower overall sample rate handling.

The situation with regards outputs is a little less comprehensive though. Output is exclusively via XLR with both fixed and variable level examples fitted. Topping says it’s perfectly ok to use XLR to RCA adapters should you need to but you’ll need to budget for those if that’s the way you want to go.

Something you do get is Topping Tune. This allows you to adjust a ten band EQ to tweak the output of the Topping to better suit the output relative to the room. What’s quite interesting about this software is that Topping has elected to make it desktop software that can be adjusted on a screen you can actually see without squinting.

From there, adjustments are communicated over USB to the device itself.  I’ve found Topping Tune a bit tricky to actually uninstall from a Mac but, if you own the D900 rather than have it turn up for review, this should be less of an issue.

In keeping with most Topping devices, the D900 has a volume control and can be used as a preamp. If you have no further interest in an analogue source, it can be used directly into a power amp or active speakers to streamline your system.

Performance

• Truly outstanding levels of detail
• Immaculate soundstage and three dimensionality
• Surprisingly tolerant of poor recordings
• Ensures you can’t hear the cleverness

Topping’s priority in their circuit design is low distortion and the best signal to noise ration they can manage; in this case a claimed harmonic distortion below -140dB and a signal-to-noise ratio of 131dB.

This is great in an abstract sense but what does it mean? When you listen to the sublime Fink Meets the Royal Concetgebouw Orchestra on the D900, the effect is subtly but noticeably different to how it often sounds. The opening Berlin Sunrise builds from silence… but on the Topping it’s not silent. In the seven seconds before the orchestra actually starts, the D900 finds the tiniest rustling and stirring of 100 plus people getting ready to perform. It’s buried in the noise floor of the recording… but the D900 finds it.

It’s not simply about these random artefacts either. As the this track builds and builds, there is a logic and order to the orchestra that makes it sound like a believable body of musicians. Different instruments play out from different sections and you can discern individual musicians rather than single body of’ strings’ or ‘brass.’  It’s the difference between a reproduction and a performance and the Topping excels at it.

It doesn’t have to be an orchestra either. Listen to the pounding and dramatic GO! on Santigold’s Master of my Make-Believe and the Topping doesn’t unpick the dense levels of production but it ensures that the whole performance is just that little more intelligible and orderly than it was before.

It does this with astonishing consistency too. Mid-seventies Trojan Records outing that sounds like it was saved to a tape and then left at the bottom of the sea? Not a problem. Absolute perfection from Blue Note? Delivered as intended. The Topping doesn’t alter or even tweak what you hear, it simply delivers more of it.

What I have found most impressive about this is how well it handles less than perfect recordings. You can give the D900 ii by Meat Puppets; a brilliantly entertaining and hugely influential album but one that is in no way shape or form hi-fi and the D900 does its work at opening it out and finding detail but the chaos and energy of the album is left intact.

This isn’t a ‘save for best’ style DAC, it’s a genuinely engaging and listenable device with all the things you choose to play on it.

The single most important thing is that you can’t hear the technology at work when you listen to the D900. For some of you reading this, this might sound anticlimactic; why go to all the effort? It reflects that the hardware is a means to an end rather than the end in itself.

It’s also worth noting that to achieve this as early on in the development of the technology is notable. Companies like Chord Electronics and dCS who also use bespoke decoding took rather longer to achieve the same feat and it represents a considerable technical achievement on Topping’s part.

Should you buy it?