This is a review and detailed measurements of the Singxer UIP-1 USB Isolator and "Purifier." It is on kind loan from a member. The UIP-1 costs fair bit at US $259.The box while utilitarian is a step above budget category:The connectivity is simple enough:For operation the UIP-1 needs an external power supply as you can see from the connector on the left. Strangely, none came with it! I am assuming they are thinking (perhaps correctly) that the market for this is audiophiles would be using fancy linear power supplies and such. For my testing, I used my Keysight/Agilent lab power supply at 7 volts.The guts show an off-the-shelf USB isolator:The white band is a required design practice to fully isolate the "dirty" and clean sides of the USB bus. The number (maxim 4930?) seems to be rubbed off however, as is the case with the IC to the left that is taking data from it. All in all looks like $30 worth of parts.Recently I tested the Meizu Hifi USB-C dongle which showed high sensitivity to USB bus noise. As much as I hate acknowledging anyone knows more than me about testing, the owner made a good suggestion of testing that DAC with the Singxer so that is what I did. Here is our dashboard with straight USB Connection:If you look to the right, we see a sea of spikes which collectively knocked down the SINAD by good many dBs as distortions were below -120 dB. If we route the USB connection through the Singxser UIP-1 we get this improved picture:There are still noise products but now their levels are below that of the harmonic distortion. Our SINAD therefore improved by a significant 8 dB. It would have improved more had the UIP-1 not inserted its own mains noise on the left of our 1 kHz tone. Those peaks are now higher than the harmonic distortion so pull down SINAD by themselves.Fortunately our hearing is not very sensitive to low frequency noise so the trade off seems good. Also note that despite my Keysight power supply being made for precision electronics work, in the past I have found that it leaks some amount of mains noise. So a bit of that may be due to the power supply. One thing you can't escape though: anytime you add another power supply to the chain, you increase your chances of getting new ground loops or mains leakage you did not have before. This is why there is almost no mains noise when I tested Meizu Hifi dongle by itself above.For a better look at the spectrum I ran the jitter test:We see what we already know. The UIP-1 reduces the noise floor (blue) and removes fair bit of spikes. But also introduces its own as higher spikes to the left.Ever since I received my new custom built gaming PC for my main workstation, the DX3 Pro which I use as daily DAC and headphone amp, has been produces pretty bad noises when no music is playing. It got so bad that I disconnected the USB and went with Toslink optical from the motherboard. That took care of the problem nicely. I thought I could test the UIP-1 and see if it could eliminate the USB noise. Alas, no success because the noise has completely vanished! Such is the vagaries of mains leakage, ground loops and such.I listened anyway and there is no audible difference whatsoever. So please don't waste your money on such gadgets if you don't have clearly audible issues.Many of these tweaks and USB regenerators do nothing. I am glad the Singxer does work and does reduce USB noise. Such functionality would not be needed of course with any quality USB DAC as even $99 ones produce exceptional performance using identical USB (noisy) connections from my PC. Should you have a nice DAC but still run into noise problems as I was with my DX3 Pro, and you can trial one of these boxes, I would be fine with it. Just don't tell me it improved the sound if you were not hearing any noises before!So no recommendation but no opposition either to Signxer UIP-1 if used in proper application.------------As always, questions, comments, recommendations, etc. are welcome.My muscles are aching from lifting and carrying all the speakers I am testing these days. They say a nice warm, daily massage may do wonders for it. Need some money to hire private sessions so please help me maintain my health byusing