So a little while ago I came across the wiki page for the Z-5500's and seen that they have Easter eggs. Weird? I know right, why not tell people of these in the manual, any way here they are, I have tried them all and only the second boost mode would not work the rest seemed to.
Easter Eggs
The Z-5500 has many "easter eggs", some aren't mentioned in the user manual.
•Boost mode This will increase the volume of the system beyond the volume knob by turning the volume knob about 180 degrees after the maximum is reached; you will see "Boost 1" all the way to "Boost 11"
•Boost mode 22 This is the same as "Boost mode" only the volume can be increased to "Boost 22" instead of 11. This can be achieved by holding down the "Mute" button on the control pod while turning the volume knob.
•Second Skin This will change some appearance aspects of the control pod. The control pod must be in standby mode to enable; holding all buttons down except "level" will enable this mode.
•Diagnostic Mode This will display advanced signal information upon switching the input, by holding down the "Input" and "Effect" buttons in standby mode.
•Volume offset This will slightly increase the volume of certain frequencies when the analog input is selected. This will normalize the volume of analog signals (direct) to match the louder sounding signal of digital inputs (optical and coaxial). To use this feature, hold down the "Mute" button and turn the volume knob. This only works when an analog input is selected. The system should be on.
•Reset to factory defaults and display firmware version This will reset the control pod to its factory defaults and also display the firmware version. To do this, hold down the "Input" and "Settings" buttons while the system is in standby. This is useful before returning or sending in for RMA.

Easter Eggs
The Z-5500 has many "easter eggs", some aren't mentioned in the user manual.
•Boost mode This will increase the volume of the system beyond the volume knob by turning the volume knob about 180 degrees after the maximum is reached; you will see "Boost 1" all the way to "Boost 11"
•Boost mode 22 This is the same as "Boost mode" only the volume can be increased to "Boost 22" instead of 11. This can be achieved by holding down the "Mute" button on the control pod while turning the volume knob.
•Second Skin This will change some appearance aspects of the control pod. The control pod must be in standby mode to enable; holding all buttons down except "level" will enable this mode.
•Diagnostic Mode This will display advanced signal information upon switching the input, by holding down the "Input" and "Effect" buttons in standby mode.
•Volume offset This will slightly increase the volume of certain frequencies when the analog input is selected. This will normalize the volume of analog signals (direct) to match the louder sounding signal of digital inputs (optical and coaxial). To use this feature, hold down the "Mute" button and turn the volume knob. This only works when an analog input is selected. The system should be on.
•Reset to factory defaults and display firmware version This will reset the control pod to its factory defaults and also display the firmware version. To do this, hold down the "Input" and "Settings" buttons while the system is in standby. This is useful before returning or sending in for RMA.