Atom HE - anyone tried the 4.4mm Pentaconn (balanced)?

Hi guys,

I bought this fantastic device - Atom HE just one month ago to pair with my T1 3rd headphone, which requires a top-quality sound source as most of the reviews said. Atom HE didn’t let me down. It helps the headphone to present clear and balanced music. So thanks to the developers of this handsome system.

Then I plugged my Xelento earphone into the 4.4mm hole, waiting to be surprised again by the sound. However, there’s a small hissing sound on the ground. I switch to JVC FW01, but the sound is still there. I changed the power line to siltech and the outlet to Oyaide R1. The sound is still there. Does anyone run into the same problem? Thanks.

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I’m waiting for delivery of my Atom HE. Your comment about hiss reminded me of a comment in a review.

“ When I ran the same test with the 10-ohm Craft FOUR CIEMS from Craft Ears does reveal a rather audible noise-floor hiss, even when muted. It seems that we have a device on our hands that is best suited for full-sized cans here – which I suspect that most prospective owners will be using the Uniti Atom for, anyhow. The Uniti Atom has an identical 4.7-ohm output impedance from each of the headphone outputs, which also suggests that we may face some frequency response niggles with lower impedance headphones and IEMs.”

Full Atom review on the Headfonia website.


All Naim amplifiers have a slight hiss. But it should not detract from your enjoyment of the music.

What I suspect here is that it is the low impedance of the headphones you mentions. The JVC is 15.5 ohm while the Atom HE documentation mentions it is suitable for headphones from 16 ohm upwards. The Xelento is 16 ohm so right on the cusp. If I don’t totally misunderstand things here I think the low ohmage of the headphones leads to the background being extra prominent.

Someone else correct me if I’m wrong.

I have an HE and both my Focal headphones the background is inaudible with balanced XLR. I don’t have any Pentaconn headphones to test with sadly.

IEMs if exceptionally sensitive or have an impedance mismatch they are susceptible to noise you are hearing more so when using balanced. Not all IEMs pair well with all amplification.

Thanks all for the information. I think these in-ear IEMs may be too cruel to Atom HE. However, I heard that IE 900 fit well without hiss. I’m considering getting one. I am curious about the sound this combination can provide.

I just ran a quick test with what I have at home while on mute.

  1. RCA out to AE1 actives: audible hiss
  2. 4.4mm to Sony MDR-Z1R: audible hiss
  3. 4.4mm yo Sony IER-M9: audible hiss
  4. XLR to Focal Utopia: silence

Actually, I just checked again, the AE1’s have an audible hiss when the HE is in standby, and only up close to the tweeter. So I suspect that is just their power amp and not the RCA output in the HE. It’s also not unlike other passive speakers.

Thanks Quaman. I’m interested in MDR-Z1R, have you tried it into 6.35mm as well? Still have the hiss on the ground?

This, also, is normal if the Atom HE does not go into full power down. If you have a USB device attached or have Server Mode set to on in the app settings the device stays partially on even when you put it to sleep.

It’s less obvious on the non balanced output.

For clarity, the hiss doesn’t impact listening. I only noticed it when specifically looking for it

Hey, got the same he + ae1 actives combination. May I ask you how you set the volume levels? I set the ae1s to max but don’t dare going north of 65% on the preamp cap, afraid something will break. Maybe at my neighbor’s.
I suspect these settings bring the ae1s close to the advertised max output, but maybe there’s more?


I have them set to max as well. It’s the only way I could ensure they were set the same.

I find 50 on the HE is more than enough for my room so I rarely go above it. I’m usually listening around 40 when using roon.

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You can set a volume limit on the Atom to stop it going past a level that would hurt or overload them.

Yep that’s what I meant by cap, thanks.
Maybe there’s a better way to go about it. Ae publishes their max input ( 1 VRMS at 1khz would lead to 104db output, 105db is max while peak is said tp be 115db) but I have been unable to find the preamp section max output for the atom, and I don’t know if the headphone max output will be the same or the data is comparable given the different ohms for speakers and headphones.

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