Our gripe with most wireless headphones is that the audio signals they transmit are lossy -- they don't transmit audio losslessly. That is, your CD-quality audio doesn't quite reach you as CD-quality audio.
Sennheiser's new £220 RS 180s are open-backed hi-fi cans but, unlike most, use a lossless wireless transmission system called Kleer. It runs over the same 2.4GHz wireless frequency as Bluetooth, but without sacrificing audio data in the same way 'tooth connections do. They operate over a bandwidth of 2.37MBps, which can carry a CD's uncompressed audio data -- 1.41MBps -- with room to spare.
But they're all moo points if the headphones themselves sound like a cow being hit by a steam train. Lucky for Sennheiser though, its high-end gear has an untarnished reputation in CNET UK's testing labs, so we have no reason to feel too much doubt.
Each of the RS 180's dynamic speaker drivers responds to frequencies between 18-21,000Hz, and have built-in rechargeable batteries with a rated life of 15 hours or more.
The headphones should be in shops from this week, and have an RRP of £220. Until we have a full review we're not going to vouch for their performance, but Sennheiser has never disappointed us in the past. We have no reason to think these will be the first to.