Open, audiophile dynamic headphones, the 1989 HD 560 Ovations (and 1991 HD 560 IIs) were Sennheiser's "Spitzenklasse" headphones until the HD 580/600s, which have a different driver. Some German writers on HiFi-Forum.de prefer the HD 560 for tonal accuracy and transparency, especially for classical music. Sennheiser still stocks the cable and cushions.
Impedance - 300 Ohms
Sound pressure at 1 KHz: 94 dB