I've read the thread from last year's forum which discusses the 10dB cut on the discrete preset so that isn't the issue.

I've connected 5.1 outputs to MA1 on a G68 and I'm still having to set all other speakers to -10dB on the Sony 550 to get the expected balance from the sub using its internal test tones or tones from a test disc. Sony and G68 both at latest firmware.

Tim