Ciúnas ISO-PS battery power supply

[Ciúnas ISO-PS battery power supply]

Take your USB device off the grid

[Italian version here]

Product name: Ciúnas battery power supply
Manufacturer: Ciúnas Audio
Cost: 250 euros (23% VAT tax added if ordering in EU tax area)(Currency conversion)

Reviewer: Nick Whetstone - TNT UK
Reviewed: March, 2018

One of the problems that many audiophiles face is getting good clean power to their audio devices, There are two solutions to the problem: one, use a good quality mains conditioner, and two, use a battery supply. Years ago, audiophiles started playing with batteries; everything from AA batteries that are used in torches etc, to full size car batteries. One of the down sides of a battery supply is that it will need recharging every so often. Even if the battery supply carries enough charge to last for a whole listening session, the user must then remember to connect the charger at the end of the session, and then disconnect it before the start of the next. So manufacturers have developed the technology to allow a charger to be connected while the supply is in use, but at the same time, not allowing the mains supply to contaminate the supply to the device being powered. One such device is the ISO-PS from Ciúnas Audio, who have developed a strong reputation for their battery powered DACs etc.

The ISO-PS will be familiar to anybody who has owned other Ciúnas Audio products as it comes in the same case. The small aluminium case ( 4.72 x 1.69 x 3.07 inches or 120 x 43 x 78 millimeters) houses user-replaceable batteries, and the electronic circuitry that not only allows the device to be used while it is being recharged, but tells the user if the device is on, charged, and ready for use. The ISO-PS can power both 5 volt, and 7 volt devices so should be able to power most USB devices on the market. When ordering an ISO-PS, the customer can specify two 5 volt outputs, two 7 volt outlets, or one of each voltage. Each output can supply up to two amps current which is enough for most hi-fi USB devices that run on DC.

There isn't a lot involved in using the ISO-PS. The review sample came already charged, but I did need to construct a suitable cable to use it with the iFi iDAC that I was going to use with it. There is a cable supplied with the ISO-PS that will connect it to a device using the standard 2.1mm DC plugs.

[Ciúnas ISO-PS battery power supply, and other portable devices.]

On turning on the ISO-PS it will beep once & the blue led flash 3 or 4 times & then stay. If any of the the batteries begin to fall below 3V the led will start to flash. And if it goes below ~ 2.5V the led will extinguish and it will beep continuously. ?

The aim of this review was to audition the ISO-PS against the power supply that I usually use with the iFi iDAC, ie a Paul Hynes SR3-5 power supply that is itself supplied through a James Audio power conditioner (sadly no longer available). This mains supply is in my opinion very good. My mains supply isn't too bad, and the James Audio conditioner takes it to another level.

I began simply by connecting the ISO-PS into the system in place of the mains supply, and doing some listening. I did notice a slight difference, and then went back to the mains supply to confirm that. Having switched back and forward a number of times, I concluded that I did slightly prefer the mains supply, and I asked myself if this was because it was what I was used to listening to. So I used the ISO-PS exclusively for three of four days, and then compared the two again. My preference was still for the mains supply. It simply sounded a bit more exciting, and I did wonder if that could be due to something inserted by the mains supply, despite the power conditioner. What ever it was, the more I listened, the more sure I was that I preferred the mains supply.

But to put this in context, it was not a case of one supply sounding better or worse than the other, and the difference was so small, that although audible, it did not mean that I did not fully enjoy the sound of the battery supply. If my mains supply was taken away from me, I could quite happily live with the sound of the ISO-PS. And at this stage, it is only right to point out that the ISO-PS costs 250 Euros, while the Paul Hynes power supply, and mains conditioner (if it were still available) would cost six times as much!

I should also mention that I tried the ISO-PS while it was receiving a charge from the charger, and while isolated from the charger, and I could hear no audible difference at all. So it can be left on charge, and simply turned on and off like any mains supplied power supply. The ISO-PS does not come with a charger so you will want something that produces 5 volts at 1 amp (or more). The ISO-PS does come with a charging lead, presumably to connect it to the Ciúnas ISO-HUB charger.

I did also bring out of retirement, a simple 5 volt battery supply that uses 4 AA batteries, to compare against the ISO-PS. The difference was quite audible with the ISO-PS sounding simply more dynamic than the AA batteries. So, I can honestly recommend the ISO-PS for those who for whatever reason prefer to, or need to, use a battery power supply. Ciúnas Audio have built up a good reputation for the quality of their USB devices over the last ten years, and the ISO-PS does nothing to harm the brand.


When John Kenny of Ciúnas Audio asked me how I had got on with the ISO-PS, he was interested in my conclusions, but suggested that the ISO-PS may work more optimally with devices that can be connected via the supplied cable, ie ones that have a separate socket for DC power instead of taking the DC in via the USB socket. The reason for that is that the power wires inside a USB cable are of a small gauge, and therefore not able to allow the ISO-PS to supply maximum power to the device being powered. I accept that this is sound theory, but at the time did not have a device that used a separate 2.1mm DC inlet. Despite the reservation, the ISO-PS still worked very well with the iFI iDac, probably due to constructing an adequate arrangement for connecting them together.

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