Violectric Niimbus US 5 Pro

In there is the delicate balance Niimbus provides. US5 Pro achieves infinite headroom for listening loud on the most demanding headphones, reproducing crashing musical crescendos without the slightest hint of clipping or losing composure. 

And at the same time, Niimbus is a transient detail monster, being totally respectful of musical detail and reproducing it without undue colouration.

“Tools, not toys” is the famous Vioelectric slogan, yet US5 Pro's top attributes always combine to bring us unbridled fun hearing detail that hadn't been present before.

At the heart of Niimbus' awesome performance is a power supply built upon a 60 volt operating voltage. No matter how loud you listen, US5 Pro's massive headroom keeps individual transistors running in their most linear region in the open-loop. 

Linearity is already a given before negative feedback is applied. What goes in comes out the same – and US5 Pro's fully-balanced, differential operation yields common-mode rejection that also lends itself to this amplifier's huge claimed 135dB dynamic range.

The true credit for that goes towards the default extremely low internal gain – all of 2dB – Niimbus works with. With lower gain comes lower noise, encouraging you to climb your volume knob and feed in more signal ... only helping your ratios, and your ability to hear more of the music. 

That optimised operation only serves up the platform for US5 Pro's reed-relay volume control – 256 steps each yielding a 0.4dB difference. That yields super-precise adjustments devoid of channel imbalances, and no loss of transparency one might otherwise endure at the lowest points of a conventional potentiometer.  

Free from the big chunk of a variable resistor in its signal path, US5 Pro switches in a couple of quality resistors of precise value for your volume setting, to enable a hyper-transparent presentation.

The direct-coupled Niimbus promises frequency extension that is virtually flat from near DC to 250Khz, meaning phase response in the human hearing range is stellar and transients and dynamics are true-to-life.

What strengthens this impression is clearly a tremendously high slew rate. The air and natural, sophisticated bloom to notes separates this Niimbus from all others – even its regular US5 counterpart.

All this exceptional handling of US5 Pro's small signal leads to a linearity that then gets passed over to 16 output transistors that are well capable of withstanding the amplifier's huge operating voltage – and handling the abundant current its power supply can deliver.

This all maintains the exceptional fidelity Niimbus receives from your source, to be passed over accurately – with minimal distortion – to your flagship headphones. 

With every other popular flaghip planar-magnetic headphone taking the low-impedance route, having the power reserves and voltage headroom of Niimbus will serve you ably now and in the future.

US5 Pro drives everything, from IEMs on the right pre-gain setting, to becoming the sweet spot for Final Audios, Focals, Fostexs and Rosson Audio Designs, to the ZMF Headphones Caldera, Hedd Audio's HEDDPhone 2 and naturally, HIFIMANs and Abyss Headphones.

Come and hear how Niimbus US5 Pro's heavy hardware and expert craftsmanship of assemblers working under Fried Reim's direction justify its top-tier pricing and place at the top of the flagship pile.

View the sibling US5 here, other Vioelectric amplifiers here, or all our other amplifiers here.