I am using the SPDIF iPurifier with an Auralic Aries Mini and a Rotel integrated amplifier that has a built in DAC. I tried several USB cables along with an inexpensive Audioquest COAX cable and I determined that I preferred the sound of my setup with the COAX cable. I then tried the SPDIF iPurifier to see if it would improve the sound. The results were very positive.
The SPDIF iPurifier made subtle but significant changes in several ways. My system sounds better with quiet, acoustic music. I guess that means that the noise floor was improved. Music with grunt, such a jazz sax sounds, has more detail. The overall sound is more smooth. Everything just sounds better.
The end result is that I improved the sound of my system for far less than the cost of a “quality” USB. The iPurifier is well worth the money.