Archimago's Musings: REVIEW / MEASUREMENTS: Drop + THX AAA 789 Linear Headphone Amplifier. And on Audioholics' THX Onyx DAC/amp "review" with a dash of MQA nonsense...
The THX Onyx USB-C dongle is a MQA with hi-res audio DAC, works with iPhones, Androids, PCs and Macs - NotebookCheck.net News
Review: The THX Onyx Portable DAC's Got Game - Twittering Machines