After the swift success of Zircon, ROCK has released the cheaper Mula. Even though the build quality is quite similar to Zircon overall, the implementation was poor, because the replaced a beautiful metallic remote with a plastic one, and stuffed the cable inside a small package, which resulted in irreversible bends along the cable.
As for the sound quality, there's barely any room for comparison. The sound is much simpler, condensed and just plain. The bass is weak and lacks any impact. The highs are quite good but the mids sound slightly inaccurate.
The quality assurance of Mula is also much worse than Zircon's, since both Mula pairs I got were defective (the other pair which I scrapped right away was extremely disbalanced), while the drivers of both Zircon pairs I ordered were perfectly matched.