Product Summary:The iFi Pro iESL is the Porsche engine of the electrostatic headphone world. Electrostatic headphones are relatively rare and exotic, even for audiophiles but if you'd like to venture down this road the Pro iESL is your performance platform.... Click To Read More
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iFi Audio – Pro iESL Electrostatic Headphone Amplifier
The iFi Pro iESL is the Porsche engine of the electrostatic headphone world. Electrostatic headphones are relatively rare and exotic, even for audiophiles but if you’d like to venture down this road the Pro iESL is your performance platform.
The Porsche and the Pro
Electrostatics need high voltages to energize them to produce sound. The Pro iESL is one such energizer and delivers the extra-high-tension voltage needed. The capacitor pack has around 35,000,000 kOhm insulation resistance, which means that self-discharge time (to 30%) is around 100,000 seconds or 27 hours.
It is one of the best energizers in the business (even if we do say so ourselves) and is compatible with all the great electrostatic brands – including Orpheus and Koss.
If you like electrostatics, then you like ‘big’ sound.
The Pro iESL won’t disappoint. Coupled with our more traditional flagship amplifier, the Pro iCAN (or any other, but we like ours), the Pro iESL lowers distortion, separates vocals, orchestras, and instruments.
It opens up the bass and leaves you with a wide, structured soundstage.
Here’s some good news.
The Pro iESL can also be used with your flagship dynamic headphones thanks to a unique transformer-coupled-stage that can take them to the max.
Just go Pro
Enjoy the pure luxurious, pleasure of flying high with your headphones – electrostatics or dynamics – with the iFi Pro iESL.
No more background noise, no more distortion. Just smooth, sexy, open audio.
Forget the Porsche – just go Pro.
The ‘Perfectly Matched’ headphone experience. Both classic and cutting-edge technology in 3 quality components delivers a perfectly matched listening experience – one-off Pinstripe Permalloy Core Transformer, a Bias Voltage Generator, and the Capacitive Battery Power Supply.
Making a transformer with the wide bandwidth and low distortion needed in the iESL is very challenging. To attain this, the custom transformers use complicated hand-wound, multi-section windings with both vertical and horizontal sectioning. They exceed the standards set by Siemens (Germany) and Peerless (USA). With a bandwidth of < 5Hz to > 60kHz (-3dB), transformers in the iESL far exceed the requirements of even the JAS High-Res logo.
So, what’s a capacitive battery power supply? This means the battery is charged up to the required voltage and then the charger circuit is turned off completely, leaving the capacitor bank to ‘float’ at the required bias voltage.
An essentially perfect bias voltage source with no electronic noise whatsoever at any frequency as the headphones are, in essence, powered by the battery bank and not the mains!
These 1,000 Volt rated capacitors are from Germany. The key is the very high insulation resistance and minimal current leakage, as any such leakage causes self-discharge. The whole capacitor pack has around 35,000,000 kilo Ohm insulation resistance, which means that self-discharge time (to 30%) is around 100,000 seconds or 27 hours. You are always listening on battery (not mains) power.
Good news for your flagship dynamic headphones. The iESL has an ear-tingling transformer coupled-stage that is not found in other energizers.
The audio performance is unsurpassed. Each and every flagship dynamic headphone, when used through the iESL, enjoys a whole new level of smoothness and airiness.
Vishay MELF resistors – complex, costly but superior. These metal electrode leadless face resistors have excellent accuracy, stability, reliability, and pulse load capability. They provide optimal power rating and pulse load capability. Nothing else comes close.
Note: We strongly recommend adding the iFi iPower Elite Power Supply anywhere else you can use an external power supply in your system. In our listening tests, the iPower Elite improved the sound so dramatically we now consider it essential. It comes with a 45-day trial period but we heard the results in about an hour.
iFi Pro iCan and Pro iESL Reviews | Swiss Army Amps
iFi Pro iESL Review
This costs a ton of money. But the build and options are why I know it’s going to work for me for … ever? I am currently pushing my L700 and 207’s with my Aune S7 pushed through the balanced input. Lots of options for those crazy Electrostats that exist. Really a special unit.
Maximum Output voltage:
640V RMS (16Ω/20V in)
320V RMS (64Ω/20V in)
Frequency Response: 5Hz – 50kHz (-3dB)
Input Voltage (Pro iESL): 5V – 9V/1A max
Input Voltage (iPower): AC 85 – 265V, 50/60Hz
Power Consumption: < 1W
Dimensions: 213(l) x 206(w) x 63.3(h) mm
Weight: 2.5kg (5.5 lbs)