I have had one for about a week now powering a Netgear GS108E network switch. The switch is feeding a SoTM sms-200 neo streamer plugged into a Chord Qutest Dac. I found an improvement in detail, depth. imaging and tone. Bass transients were better, with more body and meat and tone. Slightly better decay in the lower end also. I agree with you that it improved my sound in a subtle way but certainly noticeable. Im more than happy. I have 2 Sboosters for my streamer and Dac with the same kind of effects but more of a profound effect.
I had a quick internet search they very in output voltage, I think the maximum is 24 volt version DC, what should be enough for your phono stage, you could check with the transformer in the device and measure its voltage. If you solder the two wires on the output of the regulator even on the input but you'll get more noise so no point, and put a a barrel socket I'm assuming that's what's on the ifi?? then you can just feed a direct DC in as long as your pass the transformer..! you won't have a problem, you can still use the filter caps in the device phono stage. You won't exceed the voltage because it's a switch mode power supply
I bought one for my wiim pro plus and it does make a difference. Everything is a bit sharper, and clean sounding. My home is only 13yrs old so i have new wires my audio room is at the end of the line a living room w lights and two tvs are all before the power gets to the audio room. It does work.
