Oddly enough my friend has the cav 50 and he used to have Thiel cs 1.5's (which I now own) and never had any hiss.Later he bought some Sonus Fabers and abra-cadabra ...hiss.Not horrible, but enough to realize that it was a result of the speakers.It wasn't that the Thiels were rolling off any freq's or anything like that, they are just different.The Sonus Fabers seemed to like LP's but old recordings on CD just seemed a little hissy.