Sibilance is most of the times on the recording. Getting good quality recordings is the best way to go in orden to avoid loosing sound quality. Otherwise you should get a pretty dark-sounding/forgiving headphone. To recognize these kind of headphones you should look at some frequency response graphs and consider those hedphones with a well in the response between 4Khz and 7Khz.
You should consider:
Yamaha HPH-200. These are really forgiving open on-ear headphones. With good bass, and detailed highs, but not sibilant.
Sennheiser Hd598. Really smooth headphones. Not lively highs like Yamaha's HPH-200 but more neutral response, and relaxed sound signature with big soundstage.
Philips Fidelio L1. This are dark sounding headphones with much more energy in the sub bass region than Hd598 and HPH-200. Built quality is really good but no replaceable pads as far as I know.