You may be interested with the Receiver Editor for the Z9 if you havn't already got it, or had a look at it.
There is also a manual to go with it.
YAMAHA RECEIVER EDITOR
The only other thing is that you can get a copy of the Z9 service manual, but i think you need to purchase that one, it is not avaliable electronically, and i don't think it is made easily avaliable to the general public either.
You may find the Receiver Editor handy, it makes setting up the Z9 a breeze, and you can store a number of configurations and switch between them easily.
Anyways,
cheers
(i know that since the Z9 has been bought out, there have been at least two large firmware updates for the whole system (Aussie models, could be different for US, though probably not), Video , DSP's and the whole Z9 in general. I have no idea how to check your Z9's firmware version, and Yamaha do not make the firmware updates avaliable to the public. You also need a small peice of software called "YAV Boot V511.exe" to upload and install the firmware on the Z9, so even if you did get a hold of the firmware, you still can't do it yourself unless you get this program off Yamaha, well as far as i know from what i've found out anyway
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.)