iFi Audio Pro iESL - The Official Thread

  1. rumina
    i have the iesl since some weeks and love it. i like to build my amps myself from time to time, love the desings from nelson pass. when i start to build nelsons sony vfet amplifier i had the plan to add a voltage divider to drive my dynamic headphones. and right at this moment the iesl was available so i ordered one. would be great to listen to these great amps with my headphones.

    now i use the iesl most of the time together with the sony vfet amp and the stax sr-007. the iesl is very neutral energizer which transports the sound of the amp who is connected to your headphone. having the beautiful sony vfet sound with the sr-007 is magic for me, the frequency responce if the iesl is quite linear, deep bass up to the mids are perfect, the highs are a tad extenuated. so the iesl is a non sounding device with the ability to transport the sound of the amp.

    the limits of the iesl is the resolution but it depends on the headphone. when i compare the sr-007 out of the iesl (via the vfet amp) with the blue hawai se the resolution is quite similar, maybe a tiny bit in favor of the bhse. nothing i would miss. with the sr-009 it's different, out of the iesl you are loosing some details, responce and soundstage is perfect but you miss the last details in contrast to the bhse. these top perfoming headphones like the sr-009 or the focal utopia are not allways easy, with the sr-007 i can enjoy all my music. with the utopias an even more with the sr-009 out of the bhse a part of my music is simpy to bad recorded or mastered to enjoy. the tiny loss of resolution is similar to great tube amps (luxman) with output transformers, the effect is a small softening of the sound (and dont think at cheap tube amps).

    with dynamic headphones it's tricky, when i use a voltage divider adapter i made out of my power amps in contrast to the iesl i prefer the voltage divider. the iesl softens the sound quite a bit more then with electrostatic headephones (this effect is more audible with a easy to drive utopia, a lcd-3 sounds better out of the iesl). also the control of the bass get's a bit loose trough the iesl. with sensitive dynamic headphones you hear also the noise floor of the amp. the differences between a good voltage divider and the iesl are not enormous but audible.

    the iesl needs power and control to sound good. my 3.5 watt class a dynalo is to weak, the dynahi with 15 watt class a is perfect. the sony vfet with 20 watt stunnig. the sound quality i get out the sony vfet / iesl combo beats a stax srm-727 easy. the iesl is capable and scales up with the amp you are using. i think only a few headphones amp are potent enough for the iesl. but if you have a nice (class a) amp with around 20-50 watt and electrostatic headphones the iesl is a great joy to use. it's not a phrotesis in contrast to a standalone electrostatic amp but a great possibility to get a better match of the audio chain you are listening to.
    Last edited: Sep 12, 2017
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  2. Matez
    Ha, I have Firstwatt F7 nearby, iESL and some Kingsound estats. The only thing that's not there is time to have a proper sit down and listen. And now what you wrote got me interested to finally find a moment ot get my setup finally done. Thanks!
  3. iFi audio
    No, this will be fine. Equally, balanced sources that do not tolerate links from pin 2 & 4 (or between the L/R negative binding posts) will also be OK.
  4. Yoram Diamand
    Hi, I have a Stax sr-L700 and a srm 323A for the time being. I might think of buying the iFi if it did not work on mij power amp. It seems it is an old Stax idea which is old fashoned. Must I compare it with the Woo Wee? Perhaps iFi will once make amp that feeds on its own power.
  5. Khragon
    What impedance is recommended for the 4-pin XLR input?
  6. iFi audio
    Hi Khragon

    The effective load impedance is set using the impedance selector.

    The Amplifier driving the iESL should be able to sustain full output into the selected impedance and should have a much lower output impedance than than the nominal one, by at least a factor 5.

    I hope that this answers your query.

    Best wishes

    iFi audio Team
  7. Fastnbulbous
    I hooked mine up last night finally. I love that since it's connected to my iCAN, I don't need to plug in an additional power supply, because I'm all out of slots! Still waiting for the MrSpeakers electrostatic (too bad the instructions couldn't include those in the table of settings), so I tried it out with my HE-6. I flipped the gain on the iCAN to the highest setting (I have it on middle with just the iCAN), and it sounds good. It's slightly different than the iCAN alone, will need more time to pinpoint differences.
  8. Matez
    Lots of power on tap for your HE-6, ain't it?
  9. Khragon
    Wait how are you connecting the iESL power to iCan? photo please :)
  10. Fastnbulbous
    It's the HDMI cable provided. This was shown here:

    Yeah, it very capably drives my HE-6. There's been doubters about its ability to do that, not sure why other than it's not $6,000 like some other hardware out there. I'd like to see someone evaluate it with the Abyss too.
  11. Khragon
    Didn't realize power is delivered as part of the HDMI cable.. nice

    Question to ifi, can I use a slightly longer standard hdmi cable? I like to put the iesl and ican side by side instead of stacking them.
  12. iFi audio
    Dear Khragon

    We have found that many standard HDMI cables do not follow the actual HDMI recommendations. If a cable is assembled 100% in compliance with the HDMI recommendations, it should work.

    However we have been looking for quite a while for an affordable and suitable cable that not only works but also provides good sound quality and is short enough and have not been able to find one. This is why we include the custom cable you get with the iESL Pro.

    I hope that this answers your query.

    Best wishes

    iFi audio Team

  13. Khragon

    Will you be providing for purchase a longer version of the included cable? Double the length would work.

    Also, did you try supra hdmi? I have good experience with supra cables.

  14. iFi audio
    Dear Khragon

    We are looking into it however please do not use other HDMI as it has special wiring configuration.

    I hope that this answers your query.

    Best wishes

    iFi audio Team
  15. greenkiwi
    I can see where reusing an existing / standard plug for a different purpose could cause issues.

    Is the wiring not setup so that it will work with standard HDMI wiring?

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