Review: Niimbus Audio – US4+

Niimbus US4+

Disclaimer: Lake People sent us the US4+ for the purpose of this review on loan and it will normally be returned to Lake People. I strongly advise reading our earlier Violectric reviews first as some of the basics, like the gain settings, have been skipped in this review.

Lake People / Violectric. Again?

Long time Headfonia readers know we’re a bit of Violectric/Lake People fans here. If you’re not familiar with the brands, I suggest reading up on the previous reviews or you can check out the company’s bio on their website.

I myself have reviewed the V100, V200, V281, V800 and V850. Dave reviewed the Lake People units for us and he has covered the RS02, RS08, G109S and RS06. We loved them all. Violectric’s and LP’s popularity has only increased in the last few years and it time you see them at the shows – like in Munich – they seem to become bigger and bigger. This year they were even doing the show together with Audeze and the booth often was packed.

I first reviewed a Violectric unit back in November 2011. The V100 was so good I immediately bought it from Violectric. One and a half year later I reviewed its bigger brother the V200 and surely enough, I bought the unit. I can’t remember who I sold the V100 to but I’m convinced someone is still enjoying the hell out of it. After I did the V281 review, I bought that one and I sold my V200. Chances are I’ll be upgrading to the US4+, but financially that’s quite the step up. More on that later.

Niimbus Audio

In order to not complicate the product line-up, the people behind the company use different brand names such as Lake People (Pro gear), Violectric (audiophiles) and now the new Niimbus Audio, the high end line-up.

Nimbus is a brand/ linecard by LAKE PEOPLE electronic GmbH. The knowledge of 30 years of own development & production has flowed into the products of Nimbus.

Based on the experiences of more than three decades of Lake People development, as well as the technical and optical demands of the Violectric brand raised to a new, previously unknown quality level, the name extension of the Niimbus devices is therefore logically “Ultimate Series”. Devices with the Niimbus label stand for a special design, extraordinary technology and uncompromising quality – of course “Handmade in Germany”.

Compared to the Violectric series, the noise figure is over 10 dB better and that results in an even blacker background, more open and transparent sound, enhanced stage … and so on. A higher-end sound, so to speak.

The home page of Niimbus Audio can be found here:

Tools, not toys

This reflects the approach of developing serious technology at reference level. In the professional field, the company realizes this claim under the name Lake People, in the hi-fi sector with the brand Violectric. The entire development and production takes place in the factory in Constance, even suppliers come largely from Germany. The result is a “Made in Germany” quality seal.

Right now the Niimbus brand offers two amplifiers, the US4 and the US4+, but a prototype of the Niimbus DAC could be seen at High End a few weeks ago. It will be available in a few months from now and it has the same form (and price) factor as the unit we’re looking at today.

Did you know that Fried Reim, the man behind all these companies wrote a small book on amplification? You can find his “Headphone Amplifier Cookbook” right here for download:



The Niimbus US4+

Niimbus US 4 and US 4+ represent the uncompromising further development of the recognized, high-quality headphone amplifiers from Violectric. During the three years of development work, no compromises were made in circuit design, components or materials to create a headphone amplifier with outstanding audiophile properties. The completely newly developed channel-separated and 100% analog amplifier circuit has hand-selected audiophile components and has been optimized for lowest noise and highest performance even on particularly low-impedance headphones. In combination with the oversized power supply and the associated high supply voltage, you get an extremely detailed and tidy sound image, which plays absolutely relaxed in every setting and with every headphone and represents every nuance of the music.

The dedicated product page for the US4+ model can be found here: There’s also a great Head-Fi thread on this amp here.

Before we continue with the US4+, you should know there also is a US4 version of this amplifier. Look at it like the Violectric V281 vs V280.

Niimbus US 4 which can be seen as the enhanced Violectric HPA V280.

– Two inputs, unbalanced and balanced, to be activated from the back.
– Volume control via Alps RK27 attenuator
– balanced and unbalanced line-out connectors on the back, switchable to pre- or post-fader operation.
Thats all – a headphone amp with some basic features but outstanding sound signature.

Niimbus US 4+ can be seen as the enhanced Violectric HPA V281 with remote control and relay attenuator.

– three inputs, 1 x balanced, 2 x unbalanced, switchable from the front
– motorized volume control via 256-step reed-relay attenuator
– balanced and unbalanced line-outputs on the back, switchable to pre- or post-fader operation via software
– headphone outputs and line outputs can be de/activated from the front panel
– remote control for volume, input select, output select, mute

The Niimbus US4+ measure 350mmx280mmx80mm and weighs 7,5kg. Unlike with the V281 models, a DAC can’t be added optionally. The US4(+) is purely about amplification, but it is a pre-amp as well.

You can find all of the US4+’s features below, but the most important/eye-catching cfr. Fried Reim are:

– a volume control with nearly inaudible reed relay with 256 stages in 0.4dB steps.

– delayed switch on, instant switch off during power on/off to protect your expensive headphones from DC issues during powering on and distortions during powering off.
– DC control of the outputs to protect your headphones from unaudible DC currents which may come from the amp itself (malfunction) or the inputs
– Overload control to avoid heavy distortions generated by the amp due to too large internal signals
– enhanced Pre-Gain settings with a range of 36 dB (-12 … +24dB) to cover virtually all possible input voltages and all headphone impedances / sensitivities and provide a large travel of the volume control
– line-output voltage adaptable within a range of 24 dB (-12 … +12 dB) to ensure a matching output voltage to the following gear
– adaptable brightness of the LEDs and the illuminated gap of the volume control (only US 4+)

If you’re interested in the US4+’s circuitry, you can find it here: where it was posted by Mr. Reim himself.

This review continues on the next page here, after the click

4.6/5 - (60 votes)

Lieven is living in Europe and he's the leader of the gang. He's running Headfonia as a side project next to his full time day job in Digital Marketing & Consultancy. He's a big fan of tube amps and custom inear monitors and has published hundreds of product reviews over the years.


  • Reply June 1, 2019


    i dont think v850 would make jusctice for amp like this. This dac i below average. We get it youre fanboy of violectric but atleast try other dacs maybe? im sure Chord qutest would do much better let alone costlier dacs. Good read though

  • Reply June 7, 2019


    v850 is not a bad DAC. It does about everything right except the detail retrieval compared to others in the price range. For a detail freak like myself, it’s not an ideal DAC. But, it can be a great DAC for music lovers who focus more on the timbre, naturalness, etc. But I do agree Chord qutest is better, and I suppose that’s about the minium DAC people, who spend 5k on a headphone amp, will use together.

  • Reply October 7, 2020


    Read the owners manual, thank you L.
    It is so Fried, LoL.
    I’ve never read manuals the way they do them. Not only do you
    understand how to operate it, you learn why it operates the
    way it does.
    It was just what I needed.

    Always in the background
    Always reading around

    • Reply October 7, 2020


      Thanks for commenting 🙂

  • Reply June 7, 2022


    “In single ended mode the Utopia sounds lighter and more linear with less bass impact and overall better linearity and balance. The sound signature again is more neutral in single ended mode and the impact and body are more civilized. For some the balanced signature/synergy might be a bit much body wise, and those listeners for sure will prefer the single ended mode. I can appreciate both the balanced as well as the single ended output, and the Utopia does sound better in SE mode than the HE-1000SE does.”

    You nailed this. Absolutely nailed this. I purchased the Niimbus 5 Pro to pair with the Utopia and the body was overwhelming (compared to my Taurus MKII). I like bass but it was just too much. I was very disappointed then found your review and switched from my XLR Gravedigger cable to a SE Gravedigger Cable. So much better. You clearly take the time to listen and try different uses and to do that with multiple headphones – impressive!

    • Reply June 7, 2022


      Thank you Greg for the nice words. I have sold my Utopia in the meantime though 🙂

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