I recently finished my review of FX-Audio DAC-6. It is quite extensive. You can read it here: https://www.audiosciencereview.com/forum/index.php?threads/measurement-and-review-of-fx-audio-dac-x6-dac-compared-to-topping-d30-and-fiio-e10k.2097/ Overall, it is amazing how much you get in this little package. Mechanically this has a good feel with good heft. Lots of connectivity and headphone output with decent drive for even Sennheiser HD650. You can see how it compares to Fiio E10K at similar price point in my review and Topping D30 which remains...

I measured the iFi iPurifier S/PDIF with a number of DACs and sources of digital input from Audio Precision Analyzer to USB to S/PDIF bridges. In all cases there is either no improvement in performance or slight degradation. Full set of measurements here: https://www.audiosciencereview.com/forum/index.php?threads/review-and-measurements-of-ifi-ipurifier-s-pdif-digital-audio-filter.2189/ Here is an example of it driving the Emotiva DC-1 DAC: As seen, there are new noise products in low frequencies and the rest of the distortion spikes are...