Exploring further, I found that it wasn’t the Surface Dock, but the Ethernet cable plugged into the Surface Dock. When I pulled that, the audible noise stopped. It’s not surprising that the Ethernet cable carries lots of noise. It’s plugged into a dozen different things over tens of metres of cable. No, the problem is that the G6 should stop that noise from getting into the analogue connections.
The other weakness was with Direct Stream Digital: the volume control on the unit wouldn’t work with it. The volume control on the control software did, as did the volume control displayed in the status bar of the computer. No killer, just an inconvenience, but it should work.
I measured a few of the most important performance aspects of the Sound BlasterX G6. First, the headphone output levels. Basically, it’s a powerhouse. With low impedance headphones – I use a test load of just under 16 ohms – it managed a bit over 1.8 volts output before running into clipping. That works out to over 200mW of output. You can expect typical 16 ohms earbuds to easily go over 120dB with that output, and many to approach 130dB.
With high impedance headphones – around 300 ohms – it manages around 3.5 volts, or over 40mW. That should push most headphones above 115dB.
I did the other measurements from the line output. Here’s the frequency response with CD-standard material, it’s pretty much flat to just on 20kHz:
The noise was low at -97.6BA, THD was 0.00041% and IM distortion was 0.00036%. All those figures are as low as you’d expect from an audiophile DAC. But that’s only CD-standard audio. What about high resolution stuff?
First, here’s the unit’s frequency response with 96kHz high resolution audio. As you can see, it’s only 1dB down at 34kHz and 3dB down at 41kHz.
Running the computer on the battery, the noise was at an impressive -112.7dBA, THD was just 0.00028% and IMD was 0.00088%. Again, they are audiophile numbers. But with the Surface Pro 2017 connected to the network in my office, the noise figure plummeted to -95.1dBA. The test didn’t really capture the full amount of noise, but it still looks pretty bad on the graph. I’ve included the graph for when the Surface Pro was battery run, for when it was connected to the Dock and thence to the network, and for a $600 high fidelity DAC in both states. Yes, that other DAC still lets a lot through, but it’s orders of magnitude less.
Finally, here are two frequency response graphs for the unit with 192kHz material. I suspect I changed a setting between the two, but I’m not sure what. Anyway, the green trace with -3dB at 45kHz is pretty standard for audiophile DACs. The white trace with the response flat out to nearly 80kHz is the odd one.
The Sound BlasterX G6 promises audiophile sound and delivers it. It’ll drive just about any headphones. It’s an amazing device selling for a surprisingly low amount.
The official webpage for the Sound BlasterX G6 is here.