I used a Dual pair and a Single pair (four chips in total) to upgrade my Creative Labs Soundblaster X7 (which has sold here on Massdrop several times). And what an upgrade! Much smoother and less “hard” sound, also it seemed to help the note to note separation (or prevent the chaos of a game battle from turning into a wall of sound) and soundstage, upgrading the amp portion of the all-in-one DSP/DAC/HeadphoneAmp/SpeakerAmp device into something higher end, capable of driving the picky HD 800 (stock) without being fatiguing. This also improved the line-outputs on the back of the device.
The one downside was a sizzling sound of background noise when I first turned on the X7. Burson told me this was not typical, and fortunately it would fade and disappear after the X7 had run for a minute. Oh, and also the flap that gave access to the opamps inside the X7 didn’t fit to reattach anymore because the opamps were a little taller, but they didn’t touch the table when I set the X7 down, and I chalk it up as another non-issue.
Buying all four chips (two pairs) would have been well over $100 to upgrade the X7 when I got them, so this price is much lower than the street price I am used to. Overall, recommended!