I have a Sony TA-E9000ES DD/DTS processor. I recently added a Parasound CSE 6.1 surround "expander." THis is essentially "Circle Surround's" processor for extracting the matrixed centre surround channel plus 2 ceiling channels and some other refinements not on the Circle Surround box. Basically, the two outputs from the Sony rear channels (L-R) are inputted to the Parasound, which then outputs them plus the additional matrixed surround channels to my power amps. The problem is this; When I used my Sony alone, the rear channel residual noise level is near dead silent. Even with the volume set beyond "THX" levels, the channels (all of them) are silent except when signals hit them. When the Parasound is engaged(it has a bypass control) there is a noticeable, white noise hiss that eminates from the surround speakers. The hiss is multi-frequency, akin to white noise. This occurs no matter which surround mode Pro-Logic, DD, Sony proprietary modes I use. I is NOT volume dependent, either from the Parasound volume control for the centre surround channel or from the Sony master volume control. While this sound is not heard during surround sound signal inputs, it is noticeable during periods when the surrounds are not fed information. The unit's S.N. ratio is claimed 70db which is (IMO) high compared to the Sony's in any mode, but not so high that the hiss would be as noticeable as it is. So, I was wondering if anyone else has experienced with with "add on" 6th/7th channel boxes like the Circle Surround/Parasound unit? Or, if someone knows how I might attenuate the white noise either at line level or speaker level? Oh, in case anyone is wondering, the unit does indeed present "different" sound information through the centre surround speaker than either the left or right surround so it does work in that sense. I have not tried the "ceiling" channels yet. Thanks!