Ifi Spdif purifier

^^^^ You selectively left out an important part of the review regarding the comparison with and without an LPS:
"I should note that these are not audible problems as the levels are quite low. Just lack of good engineering and system design."

Nonetheless, still curious to know which LPS gave "astonishing" difference in the sound quality.

Sorry, I didn't see your questions until the @ notification was used.

I'm using a Swagman Labs Signature LPS, recommend by a couple of members. $280 for all premium parts built to order and a major upgrade in sound. I had good contact with them throughout the order and delivery process.

The iFi takes 5 volts. If it was mistakenly fed 12 volts, would it likely blow?

I agree with the comments about the iFi needing a better LPS. I had an old Core Audio Technology Kora around and that helped a lot, but a Paul Hynes SR4 is even better.

definitely

What the review doesn't mention is how the S/PDIF coax cable can affect jitter and the overall SQ. 
In my system using a PS Audio PWT and Audio Note NOS dac, the iFi plus LPS made a noticeable improvement. Music's more organic, spacious, has more weight, lower noise floor. I was using a variety of coax cables, always searching for one that would help achieve that analogue-like presentation.
I'm now using a High Fidelity CT-2 SPDIF and the improvement is astonishing. With this cable the sonic effect of the iFi is negligible. 

As a reminder, in the review the iFi was tested using a SMPS wall-wart. Not really a fair test for use in a high-end system. Even the designer of the Synchromesh recommends the use of a LPS.