From Mike of The Outlaws:

'm responding to the question you had regarding sound level drops in Dolby
Digital EX, Cirrus Extra Surround and DTS-ES. Due to the design of the
Model 950 and our adherence to Dolby and DTS requirements there is a global
level of drop of anywhere from 2db to 4db in these surround modes. This is
not a flaw or issue with the Model 950. Instead, it is the result of the
design of the Model 950 to meet strict requirements. Customers will
experience this drop when going from 5.1 to 7.1 modes. Simply turn up the
master volume control to compensate for the global level drop.