Silent Power USB iPurifier Pro is a USB isolator that is dedicated to use with audio equipment. According to the manufacturer, which by the way is an off-shot of iFi Audio (Silent Power is their brand dedicated to such products as various power accessories), the USB iPurifier Pro not only provides a galvanic isolation, but it also offers few more advantages. One of them is undoubtedly their “Active Noise Cancellation” technology, that should “eliminate EMI and RFI”. Which means, in more layman’s language, that it should also alleviate the problems with the ElectoMagnetic Interference (that’s where the “EMI” abbreviation comes from) as well as Radio Frequency Interference (“RFI”). On top of that is also offers their IsoGround technology which is said – and I’m quoting again – to “intelligently and safely remove excess earth connections”.
As you can see, there are quite a few marketing claims which is nothing surprising when we consider that this particular device actually has the features of three separate products that iFi Audio was offering not that long time ago. By those three I mean exactly: the iGalvanic 3.0 (which, as the name suggests, was a galvanic isolator), the iSilencer (that one was to supress the USB noise) and the iDefender (here the name is actually hard on this one – we’re talking about the ground loops avoidance). Since users were often daisy-chaining all those devices, iFi Audio decided to offer a more comprehensible solution that would pack them all in one not that very big case.
One thing that I would like to emphasize, for the sake of clarity, is the fact that this is not a USB reclocker per se. Instead, it’s purpose is to improve sonics by more passive ways (more on that later) and be useful in some more, as I would say, objective scenarios. By the latter expression I mean that it should alleviate problems with noise and other hearable artifacts that are often present in the source to DAC systems. That may especially be true when such source is your typical laptop or a motherboard in, say, even elaborate gaming computer. All of these components usually get their power from the SMPS power supplies, which means that they also generate all that noise that then goes both to the power-grid side of things as well as to those powered by that SMPS gear.
Not to mention the fact that your typical digital source is by its very nature simply a noisy environment. Especially when we talking about PC motherboards that sport a lot of parts and considering the fact that also PCI-based graphics cards can be source of the noise-related troubles that just finds it way to the USB ports (interestingly, quite some time ago one of the motherboards’ manufacturers did try to address that problem with the audio-dedicated USB ports, but that solution didn’t get much interest). Obviously, getting rid of the noise and all the digitally generated artifacts is one thing. The other one is that you may actually want to have the galvanic isolation for other reasons. Sonic improvement being one and more subjective one, and actually protecting audio components being the other. It retails for around 250 Euro, so I decided to give it a shot, especially bearing in mind that I had some problems with the objective side of things in my desktop system that I use – also for doing reviews – on a daily basis. So, let’s get down to it.
Silent Power USB iPurifier Pro – design and build
This thing is relatively small, albeit much bigger than your typical dongle. It’s design is typical for the new breed of SilentPower’s product. It’s rather understated, but in a good way, since it’s actually suggests that all the work went into inner side of things instead of being too flashy outside. We have quite a few sockets and two LEDs here, so let’s start with the description of how do we connect the whole thing. Let’s start with the fact that one thing of the device is dedicated to USB inputs and the other to USB outputs. While the inputs are provided in both the USB-C and USB-B flavours, the outputs are USB-A only. Silent Power went a little orthodox on this one, which is interesting in the light of the fact that they did provide a USB-C input indeed. As for the outputs – one is both power and data and the other one is power only. This is quite possibly also to accommodate their Gemini 3.0 split USB cable that has two connectors on the source side (one dedicated for power and the other one for data – then those streams run to the receiver by the means of two separate physical cables). While the USB iPurifier Pro is not a USB reclocker it’s a galvanic isolator indeed. When asked about how it that accomplished, Silent Power people say:
“the galvanic isolation is achieved via a Transformer. It uses one of the newer models of USB galvanic isolation ICs.”
And they also add more about that:
“USB power is often quite “noisy”, so the USB power input allows you to use an isolated power supply instead. When this is connected, the power from the USB connection is disconnected, and the end-point device will be powered from the connected power supply.”
We can all agree with their argumentation. Yet apart from all the USB ports on the USB iPurifier Pro there are also two additional ports. One is for external USB power, in that case you can connect any sensible (possibly audio-oriented) power supply that has the 5V output. In my case I used the iPower 2 – more on that in the next section. And the last and possibly most interesting connector is what is called in the manual an “Intelligent Earth Connector”. As the Silent Power people say”
“To connect other audio devices to the USB iPurifier Pro’s ground connection, if they don’t already have one. Use this ground terminal to earth the downstream system, if desired or needed.”