I recently finished my review of FX-Audio DAC-6. It is quite extensive. You can read it here: https://www.audiosciencereview.com/...c-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 my choice for a stand-alone DAC (at higher price).

Here is a sampling of measurements:











I also performed a hardware teardown of the FX-6 here: https://www.audiosciencereview.com/...are-teardown-of-fx-audio-dac-x6-usb-dac.2115/

The picture there, pun intended , wasn't as rosy. Crusty rusty parts shouldn't be there regardless of price. I am not holding my breath for long term reliability.

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/...i-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 exaggerated a bit.

To be sure, if I induce jitter over S/PDIF cable, it will eliminate those:



But much of the jitter I measure in DACs these days is internally generated, not from input. Here is for example a $29 DAC:



The induced jitter spikes are eliminated but nothing is done about the horrible amount of jitter and noise products this DAC has.

For computer use, it is hard to recommend this product. An asynch USB interface is liable to produce better quality than using the iPurifier. See these measurements comparing the two: https://audiosciencereview.com/forum/index.php?threads/battle-of-s-pdif-vs-usb-which-is-better.1943/

Don't even think about using this with a high quality DAC. I tested the Exasound E32 and as expected, iPurifier made its response slightly worse, not better. Save your money and put it toward a good USB DAC and you will be golden.