Is the CJ a "PV12" or "PV12L"? If it is a PV12, that input has an extra gain stage and is for phono only. The PV12L has the AUX input. If yours is the PV12, then use a different input.
reubent is correct, The Oppo does have a variable volume out, which is default. Turn to max or set to fixed in the menu. Also, make sure downmix is set to stereo in the menu.
Sorry, no ideas on the Oppo shutting down.