The venue was Central Hall Westminster in London, and as well as displaying a host of products from the company's history, Sennheiser held a special concert to celebrate its 70th birthday - and show off some rather clever live-music technology.

On stage was the Junge Deutsche Philharmonie orchestra, conducted by Jonathan Stockhammer, and Grammy-winner Imogen Heap. The concert was recorded by 103 microphones and mixed in 9.1 surround sound.

Sennheiser's overall aim is to create a more immersive way of recording and then presenting live music, even when down-mixed into stereo. Sennheiser believes this to be the next step in the evolution of live music reproduction.

But for many of us, that was something of a sideshow…

Elsewhere in the building, in a darkened room, a bright beam of light was fixed on a slab of stone. And this was Sennheiser's very special new product - about which we we were told only so much.

On top of the slab sat two shiny black boxes, one of which was adorned with metallic panels. The front, meanwhile, featured metallic discs. When activated, the discs protrude, revealing themselves to be dials.

Out of the metallic panels, eight valves rise up. It now appears this thing is an amplifier. Then a lid flips open, revealing a pair of very comfortable-looking headphones. As you might have guessed.

What is it? Sennheiser is keeping tight-lipped for now, and has shared only three pieces of information:

That’s no ordinary stone – it is fine Carrara marble of the type once used by Michelangelo. It was chosen for its mass, purity and solidity. It houses an amplifier and is the foundation for this device.

The headphones use 2.4-micrometre thick, platinum-vapourised diaphragms. Sennheiser’s research suggests this is the optimal size for sound reproduction.

There is an ultra-wide frequency range from 8 Hz to more than 100 kHz. That far exceeds the human auditory range; you couldn't perceive it all unless you had the combined hearing abilities of bats and elephants.

Why? This is clearly more of a statement than a consumer product. And one the Sennheiser brothers are naturally very happy with and excited about. Sennheiser CEO, Dr. Andreas Sennheiser, calls it "a new benchmark in excellence in the high-end audio world".

Daniel Sennheiser, also CEO of Sennheiser, added: “Sennheiser has had seven decades at the cutting edge of audio by defining the gold standard of what is possible. We are announcing a new phase of even higher ambition.”

Desperate for more details? We'll have all the details nearer the official launch, which is scheduled for November.

So, any guesses? And what are your first impressions from the pictures? Let us know in the comments below.

See all our Sennheiser news and reviews