D
Dan Nagar
Audiophyte
thats definitely an option - for example - Dirac adds about 6db boost the when its engaged, that can add hiss if there a gain structure issue between pre/pro.Or it's not Audyssey causing the hiss particularly, but rather the pre-pro manufacturer who installed it. I have a variety of avrs with Audyssey, hiss has never been an issue (and it would be for me if it was the cause, I'd return the electronics).
ps in reading many many threads on the subject, can't say anyone else reported hiss except you.