Rich Trenholm/CNET

LONDON -- Sennheiser has unveiled a new...something. To celebrate its 70th anniversary, the German headphone and audio company has given us a look at a new high-end audio product without telling us much more -- except that it's made of marble.

What it looks like is a headphone amplifier, and a very posh one. When you press a button, the top opens and the headphones smoothly slide out, while the amp valves emerge alongside and light up. When you're not listening, the headphones and valves disappear smoothly back into the body.

The amplifier housing is made from Carrara marble and packs 2.4-micrometer platinum-vapourised diaphragms. It promises a frequency range of 8Hz to more than 100kHz, which Sennheiser says exceeds the range of the human ear.

The unnamed marble device harks back to Sennheiser's outrageously expensive Orpheus headphones and amp from the early '90s. We know that this device will also be a very high-end audiophile product, with a price tag to match. The company will shed some light on the exact details at the Sennheiser website in coming weeks and months, telling us we'll see it properly in November.

The mystery device was unveiled at an event a stone's throw from the UK houses of parliament, with a guest appearance from musician Imogen Heap. The performance was recorded in a new audio format being developed by the company, currently known as Sennheiser 3D audio format. It's a working title.

Once again, more details of the audio format are expected to follow.

Sennheiser was founded in 1945 as Laboratorium Wennebostel (Lab W) by a team of engineers including Fritz Sennheiser, and the company is still owned by the Sennheiser family. The first product produced was a voltmeter, followed by microphones and later headphones -- including the world's first open headphones in 1968.