BIZARRE Onkyo PORT JIG of TX-SR608 FW-Update

[svhs]

Preparation for Update-1
3. Connection: DIGITAL (OPTICAL/COAXIAL) ourput of PC/CD Player --> DIGITAL (OPTICAL-1/COAXIAL-1) INPUT of TX-SR608 etc.
Connection Example
* PC needs to be able to handle wav files and output digital audio signal.
* For wav-compatible PCs which do not output audio signal at the above specification,
use a commercially-available USB-AUDIO interface unit. e.g. Onkyo-made ND-S1
* PC needs to run Windows XP. Windows Vista and Windows 7 do not work.
* Set wave Volume to Maximum including Volume Control in Control Panel

[ChrisW6ATV]

That is indeed an unusual way to install a firmware update into a piece of equipment.