Hi badkarma
From the Onkyo TX-SR605 User Manual Page 84
HDMI Audio Out
This preference determines whether audio received at the HDMI IN is output by the HDMI OUT. You may want to turn this preference on if your TV is connected to the HDMI OUT and you want to listen to the audio from a component that’s connected to an HDMI IN, through your TV’s speakers. Normally, this should be set to Off.
Off: HDMI audio is not output (default).
On: HDMI audio is output.
Notes:
• If On is selected and the signal can be output by the TV, the AV receiver/AV amplifier will output no sound through its peakers.
• When TV Control is enabled, this setting is set to Auto.
• With some TVs and input signals, no sound may be output even when this setting is set to On.
You might want to check this setting on the amp
Mede8er1