Topping

DX9 DAC/ Headphone Amp

USD $1,299

Although best known for producing keenly priced electronics, Topping also makes higher-priced, more exotic fare like the DX9, a limited-edition headphone amp with state-of-the-art electronics. Seen here, it's a special edition to mark the company's fifteenth anniversary.

There are outputs for three sets of headphones via 4.4mm and 6.35mm jack plugs or 4-pin XLR. The DX9 also doubles as a DAC or preamp, offering a broad choice of digital inputs, plus fixed/variable balanced and single-ended analogue outputs to partner a power amp or preamp.

An electronic volume control allows 100 level adjustments in fine 0.5dB increments, from 0dB (max) to -99dB, while a pair of colour LCDs provide a visual indication of volume level and sampling rate. You even get the option of level gauges, including faux classic VU meters!

Available in black or silver, the DX9 features CNC machined aluminium casework measuring 340x225x60mm. The tempered glass top panel window is a nice touch, which lets you see inside the unit. The innards can be lit up or left dark, and users can select three brightness levels.

UP CLOSE

The DAC is built around the rare and legendary 32-bit AK4499EQ chip, produced by AKM and available once again after the disastrous fire that destroyed its factory in October 2020. It has four independent channels, giving the equivalent performance of two flagship AK4499EX chips. Full PCM support (to 768kHz on USB) and native DSD512 are offered via pairs of optical and coaxial S/PDIF inputs or a single XLR AES/EBU input, plus USB. There's also an IIS LVDS input via an HDMI socket. This keeps the datastream and various clock lines separate for better results. As I have a PS Audio Perfectwave CD transport with an i2s output socket, I'd hoped to use this. Alas, the pairing didn't work, as the two wouldn't talk to one another.

The analogue output amplifiers of the DX9 employ discrete components rather than op-amps. There are six independent amplifier modules. Max output on the analogue line-outs is 2.1V (RCA single-ended) or 4.2V (XLR balanced), which should be sufficient for most power amps. The headphone amp can deliver up to 10W into 16 ohms or 7W into 32 ohms, enough to easily drive even highly inefficient headphones. A quoted signal-to-noise ratio of 127dB (RCA) or 132dB (XLR) makes this to-all-intents-and-purposes silent in terms of hiss and hum.

The DX9's casework gets mildly warm after an hour or so of use. But actual warm-up time seems pretty minimal. Sonically, the unit performs very well from the moment it is switched on – if there is any further improvement after extended use, it's very slight. Changing over to Topping's DX9 from the Auralic Altair G2.1 DAC/streamer I usually use was very straightforward. The G2.1 costs $5,489 USD but also includes a streamer, a moving magnet phono stage, and a line input. PS Audio's Perfectwave CD transport was my source – connected via a coaxial cable.

THE LISTENING

Despite that significant price difference, the DX9 more than held its own against the Auralic G2.1. Indeed, the Topping actually sounded slightly cleaner and better separated, with a small reduction in digital hash – that slight sense of 'glare' you often get with CD. This was noticeable on recordings with period instruments like the nineteen eighties Mozart piano concertos cycle on DG/Archiv with Malcolm Bilson. Early digital recordings like these can sound shrill and edgy, but the DX9 ensured a clean string tone and a beautifully transparent overall sound.

This firm, clean, focused performance created a satisfying sense of solidity. While the difference wasn't 'night and day' over the Auralic, an improvement in purity was definitely apparent when listening critically. Yet there was nothing rich or rose-tinted about the DX9's presentation. On the contrary, it was always lucid rather than warm and euphonic, with impressive clarity and tight, crisp precision. Drums and cymbals had plenty of attack, plus a welcome lack of smearing, while bass was taut and deep.

Playing Rickie Lee Jones' Flying Cowboys, the sound was notable for its mix of punchy highs and firm, powerful lows. The whole production was tight and snappy, yet voices had a nice creamy timbre rather than everything sounding overly sharp and etched. The Auralic is among the cleanest-sounding DACs out there, so anything that equals or betters it even slightly is doing well. Despite the price chasm, the DX9 more than stood its ground and sounded splendiferously impressive.

Like many modern DACs, the Topping offers users a choice of digital filtering options – six in total. However, I found it difficult to discern much change in sound quality between them. Any difference between the default setting and the others proved extremely subtle. The Altair G2.1's four digital filters delivered more audible changes, and naming them 'Precise', 'Dynamic', 'Balance', and 'Smooth' is more helpful than Topping's rather technical 'Short Delay, Sharp Roll Off' style of description.

Something that did make a difference to the DX9's sound quality was switching off the unused outputs. Because each output has its own independent amplification stage, turning off those not in use reduces the load on the power supply. So, if you're using the DX9 mainly as a DAC or preamp, switch off the headphone outputs and select only the output (RCA or XLR) being used. For critical headphone listening, turn off the other (unused) headphone outputs, as well as the line-level balanced and single-ended outputs. When this is done, the music sounds more focused, with better microdynamics and fine detail. Should you listen with everything on, the sound will still be good, but the bass won't be quite as firm and tight, and the music will lose some bite and snap.

Auralic's Altair G2.1 features a high-quality headphone amp with a 6.35mm socket. To allow speedy comparisons between the GX9 and G2.1, I used Dan Clark Expanse headphones with the aforementioned jack plug cable. The G2.1 did a good job but proved no match for the GX9. The Expanses' low sensitivity meant I had to use the Altair G2.1 at (or near) full output to get just-adequate volume levels.

The GX9 delivered about 5dB more level and sounded punchier and more dynamic. It was vivid, immediate, detailed and transparent. While the Auralic set to maximum output was sufficiently loud much of the time, there was no extra gain available to compensate for low-level recordings. Later, I replaced the single-ended cable with an XLR type to allow the DX9's balanced output to be used. This produced a sizeable improvement – the sound was even more dynamic and transparent, and there was about 3dB more loudness, enabling the DX9 to pull further ahead of the G2.1. The impression was of a bigger, more immediate sound with added presence.

Via the DX9's XLR balanced output, the Dan Clark Expanse headphones sounded extremely tactile and detailed, yet smooth and well-balanced, too. They delivered clear, truthful, unexaggerated reproduction with no apparent tonal colouration. Just for fun, I dug out my old Stax SR-4070 closed-back electrostatic headphones for comparison. These almost equalled the Expanse for transparency, but seemed a tad over-bright and peaky. They weren't nearly as smooth and natural. While the Expanse headphones sounded great with a 6.35mm-socket cable, using them balanced took things to a higher level.

Clearly, then, the DX9 is aimed primarily at serious headphone users. But the DAC is so outstanding that it would almost be worth buying for this alone. I spent a long time comparing the DX9 back and forth to Auralic's G2.1, and there's no doubt the Topping has some special qualities. There's superior clarity when the music gets quiet, so backgrounds seem darker. You really notice this on wide dynamic range recordings of classical music. While these sonic differences might be subtle, once identified, they are beguiling and addictive.

To try and narrow the gap, I re-evaluated some settings on the Auralic – trying the different anti-aliasing filters and choosing whether or not to keep it in oversampling mode. I was trying to fine-tune the G2.1 to bring it closer to the DX9 in terms of bite, immediacy, and refinement. Changing the former's anti-aliasing filter from 'Smooth' to 'Precise' helped. However, regardless of the changes made, there was always a certain extra something about the DX9 that couldn't quite be replicated. It lets you hear deeper into recordings.

THE VERDICT

Topping's new DX9 is an excellent product that offers state-of-the-art performance and solid build quality at a keen price. For the exacting, discerning headphone user, it's a no-brainer. But used purely as a DAC, the DX9 is also well worth considering. This product doesn't just celebrate its manufacturer's fifteenth anniversary; it showcases Topping's ability to create well-crafted, technically superb products that compare favourably with the best offerings of its rivals. Praise be for that, then. Here's to the next fifteen years!

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