Audeze isn't the first company to release such an attachment -- Shure has a pendant that lets its IEMs work wirelessly -- but Audeze's approach here is neat nonetheless. The new cable is short, and is intended to hook around the back of your neck. It has two modules attached, which rest a couple of inches below your ear on both sides. One module houses the DAC, controls, Bluetooth receiver and a Micro-USB charging port, while the other is taken up entirely by a battery. The result is a design that, once connected to the headphones, looks like they've always been this way, rather than a retrofitted mess.
The Cipher Bluetooth Module supports Bluetooth 5.0, and Audeze claims it will last for eight hours on a single charge. Needless to say, I'm over the moon. I should get the same fit and sound that I love, but now my headphones will work with anything that supports Bluetooth audio output. For me, that's worth the $99 Audeze is asking -- I would guess that many others will feel the same.