In clean condition. Released in the mid-80s, the HD540 was Sennheiser’s flagship and top of their open line. A lot of variants existed ; different variants of Reference 1 (300 Ohm, 600 Ohm, different headbands, pads), the HD540 Gold (basically a limited run HD540 with better matched drivers, gold housing and nice wooden box), and the HD540 Reference II. New padding installed. The HD560 Ovation later came, followed by the HD580 Precision in 1993. The HD540 is extremely comfortable and light (only 207g, and they’re not small), but feels as cheap as some $5 toys. The 600 Ohm model requires quite more voltage than an HD600. ○ Release : 1986 ○ Current status : Discontinued ○ Type : Over-ear / Open-back ○ Measured weight : 207g ○ Impedance : 600 Ohms ○ Sensitivity : 94 dB/mW Insured shipping