Impressions: iFi's Pro iESL

Apologies for how long it has taken me to get these impressions up; I've had this device for the past two weeks or so, and have been using it pretty intensively, but have had so much extra on my plate, sheerly through coincidence, that it's taken me this long to get this slotted to post (it's been written for about a week). iFi strikes again with their second, and very new, addition to their "Pro" lineup. It has the same mind-boggling attention to detail that the Pro iCan does, and I've loved every second of using it.

I'd like to thank iFi, aside from for sending me their less-than-a-month-old new flagship device, for sending me a pair of King Sound's KS-H3 Electrostatic Earspeakers. iFi is not related to King Sound but they were generous enough to do so simply so that I could provide this review. Working with iFi in a reviewing capacity has always been an absolute pleasure.

So let's start at design. It has a looking-glass, very similar to the Pro iCan, but this one showing the massive transformer that the energizer uses to provide the potential difference required to drive electrostatic headphones. It certainly looks pretty, just like the Pro iCan's looking glass does.  The venting design, as pictured, is also similar the Pro iCan.

Now my initial worry was this: with a set-up as expensive as this (the Pro iCan driving the Pro iESL driving the KS-H3), would I be able to attractively stack the amplifiers? I know, petty, but at this price, everything should be perfect, yes? The worry popped into my mind because of the looking-glass on the Pro iCan, I thought it might tilt the Pro iESL off kilter. Thankfully, iFi accounted for this, and formed a divet in the bottom of the Pro iESL's rubber mat, allowing it to sit pretty and flush. I wasn't expecting to put a whole paragraph aside from that, but it was something that struck me as the exact attention to detail that one would expect from a product in this price category.

Now onto the actual performance of this energizer. For those that are in the dark here, the reason that this separate, expensive device is necessary is that electrostatic headphones basically require a very high potential difference across their membrane in order to create enough movement to move enough air to create music. This requires a massive, and very clean transformer to take your 110V AC and turn it into 540V DC.

Here's where I have to say "regrettably": regrettably, I am still learning a lot about this product. I am plainly and admittedly new to electrostatic headphones as a category, and am learning as much as I can. In both the full review of this product and of the Pro iESL, even if takes a little extra time, I will come with a much wider knowledge base to give you all a better perswpective on these products.

Here's what I do know now: this product can drive the KS-H3 with great fidelity, no problems or hiccups. The signal is sent from the Pro iCan through an HDMi cable to the iESL-Link port on the Pro iESL. Then, through (in King Sound's case) a 5-pin Pro Bias connector. The volume can be comfortably controlled via the remote, from the Pro iCan, making it functionally somewhat like a preamplifier.

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I haven't heard any inconsistencies or general unpleasantness from the iESL as of yet, and I'll be sure to keep checking for it. Again, when the full review of both the earspeakers and the energizer are posted, they will include much more information and a larger, more informed perspective for everyone reading.