Jürgen Kraus, editor of AudioReviews.org, is a fan of our DragonFly DAC. He has owned several iterations, from Black to Cobalt, the latter of which has been his go-to reference since its release in 2019. In his review of Cobalt, he concluded unambiguously: "Quite frankly, I had not expected the DragonFly Cobalt to sound this good. Considering its qualities, the Cobalt is my new standard for miniature portable dac/amps."
Jürgen's unwavering appreciation for DragonFly is based on years of experience, seemingly boundless curiosity, and thoughtful analysis — of DragonFly itself and against other worthwhile devices in its category. Jürgen knows his way around a dongle. See, for instance, his "1001 Critical Facts About Dongles," and its insightful companion piece, "The #1 Dongle Dilemma: Power vs Compatibility."
Jürgen is also a fan of our JitterBug USB filter. He owns not one, not two, not three, but five of the little buggers and puts them to good use throughout his various systems. In his review of JitterBug, he concluded unambiguously: "JittterBug FMJ removes EMI, RFI, and switching noises — which helps maintain better low level detail because the DAC chip can reproduce information better.... [I]t improved sound quality in most of my applications to the point I don’t want to miss it."
Jürgen is perhaps especially a fan of DragonFly and JitterBug used in series, but, as explained in the Q&A conducted by AQ dealer Home Automation Designs and DragonFly designer Gordon Rankin, Jürgen's preferred DragonFly Cobalt and his beloved JitterBug FMJ were not always fast friends.
Gordon: "Cobalt contains some of the filtering technology featured in JitterBug, and it’s generally inadvisable to use two filters in series, so partnering Cobalt with JitterBug didn’t always produce desirable results."
In Jürgen's review of DragonFly Copper, he happily reports that our DAC and our USB filter may once again be used together, in series and without qualification, for ultimate rejection of high-frequency noise and naturally beautiful sound.
Jürgen rejoices in Copper's ability to satisfyingly drive even relatively power-hungry headphones and in-ear monitors, including his preferred 18-ohm Sennheiser IE 900s. Further, compared to DragonFly Cobalt, Copper exhibits an alluring combination of tighter, better-controlled bass and more energetic upper midrange, resulting in improved cohesion, imaging, and attack.
With JitterBug, Copper sounds even better: weightier, more robust, and more relaxed with no loss of coherence or resolution.
And, of course, Jürgen compares Copper to his drawerful of similarly sized dongle-DACs to find that, despite its relative simplicity and modest feature set, Copper comes out "ahead in terms of natural music reproduction." Interestingly, he notes, "Copper produces a quality of spatial reconstruction with its single-ended circuit that the competitors need a balanced circuit for."
He concludes unambiguously, "[DragonFly Copper] is here to stay and it will certainly survive the acquisitions of several generations of much pricier in-ear monitors and headphones. It is that good!"
