Headphone enthusiasts—indeed, audio enthusiasts of all stripes—tend to take a dim view of wireless audio, but Sennheiser hopes to convert them with the $599 RS-220, probably the first wireless headphones designed for true audiophile quality. The RS-220 is voiced “somewhere in between an HD600 and an HD650,” a company spokesperson told me, referring to two of the company’s well-regarded audiophile ’phones. In fact, the company provided an HD650 for direct comparisons with the RS-220, and I have to say that while the two weren’t identical (the HD650 had a bit more top end but didn’t necessarily sound better), the RS-220 sounded excellent. The wireless base unit has analog, coaxial digital and optical digital inputs (selectable from a button on the headphones). The base charges the headphones, which are rated to run 6 to 8 hours on a charge.